diff --git a/vendor/go.uber.org/zap/.codecov.yml b/vendor/go.uber.org/zap/.codecov.yml
new file mode 100644
index 0000000..8e5ca7d
--- /dev/null
+++ b/vendor/go.uber.org/zap/.codecov.yml
@@ -0,0 +1,17 @@
+coverage:
+  range: 80..100
+  round: down
+  precision: 2
+
+  status:
+    project:                   # measuring the overall project coverage
+      default:                 # context, you can create multiple ones with custom titles
+        enabled: yes           # must be yes|true to enable this status
+        target: 95%            # specify the target coverage for each commit status
+                               #   option: "auto" (must increase from parent commit or pull request base)
+                               #   option: "X%" a static target percentage to hit
+        if_not_found: success  # if parent is not found report status as success, error, or failure
+        if_ci_failed: error    # if ci fails report status as success, error, or failure
+ignore:
+  - internal/readme/readme.go
+
diff --git a/vendor/go.uber.org/zap/.gitignore b/vendor/go.uber.org/zap/.gitignore
new file mode 100644
index 0000000..08fbde6
--- /dev/null
+++ b/vendor/go.uber.org/zap/.gitignore
@@ -0,0 +1,28 @@
+# Compiled Object files, Static and Dynamic libs (Shared Objects)
+*.o
+*.a
+*.so
+
+# Folders
+_obj
+_test
+vendor
+
+# Architecture specific extensions/prefixes
+*.[568vq]
+[568vq].out
+
+*.cgo1.go
+*.cgo2.c
+_cgo_defun.c
+_cgo_gotypes.go
+_cgo_export.*
+
+_testmain.go
+
+*.exe
+*.test
+*.prof
+*.pprof
+*.out
+*.log
diff --git a/vendor/go.uber.org/zap/.readme.tmpl b/vendor/go.uber.org/zap/.readme.tmpl
new file mode 100644
index 0000000..c6440db
--- /dev/null
+++ b/vendor/go.uber.org/zap/.readme.tmpl
@@ -0,0 +1,108 @@
+# :zap: zap [![GoDoc][doc-img]][doc] [![Build Status][ci-img]][ci] [![Coverage Status][cov-img]][cov]
+
+Blazing fast, structured, leveled logging in Go.
+
+## Installation
+
+`go get -u go.uber.org/zap`
+
+Note that zap only supports the two most recent minor versions of Go.
+
+## Quick Start
+
+In contexts where performance is nice, but not critical, use the
+`SugaredLogger`. It's 4-10x faster than other structured logging
+packages and includes both structured and `printf`-style APIs.
+
+```go
+logger, _ := zap.NewProduction()
+defer logger.Sync() // flushes buffer, if any
+sugar := logger.Sugar()
+sugar.Infow("failed to fetch URL",
+  // Structured context as loosely typed key-value pairs.
+  "url", url,
+  "attempt", 3,
+  "backoff", time.Second,
+)
+sugar.Infof("Failed to fetch URL: %s", url)
+```
+
+When performance and type safety are critical, use the `Logger`. It's even
+faster than the `SugaredLogger` and allocates far less, but it only supports
+structured logging.
+
+```go
+logger, _ := zap.NewProduction()
+defer logger.Sync()
+logger.Info("failed to fetch URL",
+  // Structured context as strongly typed Field values.
+  zap.String("url", url),
+  zap.Int("attempt", 3),
+  zap.Duration("backoff", time.Second),
+)
+```
+
+See the [documentation][doc] and [FAQ](FAQ.md) for more details.
+
+## Performance
+
+For applications that log in the hot path, reflection-based serialization and
+string formatting are prohibitively expensive &mdash; they're CPU-intensive
+and make many small allocations. Put differently, using `encoding/json` and
+`fmt.Fprintf` to log tons of `interface{}`s makes your application slow.
+
+Zap takes a different approach. It includes a reflection-free, zero-allocation
+JSON encoder, and the base `Logger` strives to avoid serialization overhead
+and allocations wherever possible. By building the high-level `SugaredLogger`
+on that foundation, zap lets users *choose* when they need to count every
+allocation and when they'd prefer a more familiar, loosely typed API.
+
+As measured by its own [benchmarking suite][], not only is zap more performant
+than comparable structured logging packages &mdash; it's also faster than the
+standard library. Like all benchmarks, take these with a grain of salt.<sup
+id="anchor-versions">[1](#footnote-versions)</sup>
+
+Log a message and 10 fields:
+
+{{.BenchmarkAddingFields}}
+
+Log a message with a logger that already has 10 fields of context:
+
+{{.BenchmarkAccumulatedContext}}
+
+Log a static string, without any context or `printf`-style templating:
+
+{{.BenchmarkWithoutFields}}
+
+## Development Status: Stable
+
+All APIs are finalized, and no breaking changes will be made in the 1.x series
+of releases. Users of semver-aware dependency management systems should pin
+zap to `^1`.
+
+## Contributing
+
+We encourage and support an active, healthy community of contributors &mdash;
+including you! Details are in the [contribution guide](CONTRIBUTING.md) and
+the [code of conduct](CODE_OF_CONDUCT.md). The zap maintainers keep an eye on
+issues and pull requests, but you can also report any negative conduct to
+oss-conduct@uber.com. That email list is a private, safe space; even the zap
+maintainers don't have access, so don't hesitate to hold us to a high
+standard.
+
+<hr>
+
+Released under the [MIT License](LICENSE.txt).
+
+<sup id="footnote-versions">1</sup> In particular, keep in mind that we may be
+benchmarking against slightly older versions of other packages. Versions are
+pinned in zap's [glide.lock][] file. [↩](#anchor-versions)
+
+[doc-img]: https://godoc.org/go.uber.org/zap?status.svg
+[doc]: https://godoc.org/go.uber.org/zap
+[ci-img]: https://travis-ci.org/uber-go/zap.svg?branch=master
+[ci]: https://travis-ci.org/uber-go/zap
+[cov-img]: https://codecov.io/gh/uber-go/zap/branch/master/graph/badge.svg
+[cov]: https://codecov.io/gh/uber-go/zap
+[benchmarking suite]: https://github.com/uber-go/zap/tree/master/benchmarks
+[glide.lock]: https://github.com/uber-go/zap/blob/master/glide.lock
diff --git a/vendor/go.uber.org/zap/.travis.yml b/vendor/go.uber.org/zap/.travis.yml
new file mode 100644
index 0000000..a3321fa
--- /dev/null
+++ b/vendor/go.uber.org/zap/.travis.yml
@@ -0,0 +1,21 @@
+language: go
+sudo: false
+go:
+  - 1.9.x
+  - 1.10.x
+go_import_path: go.uber.org/zap
+env:
+  global:
+    - TEST_TIMEOUT_SCALE=10
+cache:
+  directories:
+    - vendor
+install:
+  - make dependencies
+script:
+  - make lint
+  - make test
+  - make bench
+after_success:
+  - make cover
+  - bash <(curl -s https://codecov.io/bash)
diff --git a/vendor/go.uber.org/zap/CHANGELOG.md b/vendor/go.uber.org/zap/CHANGELOG.md
new file mode 100644
index 0000000..17d5b49
--- /dev/null
+++ b/vendor/go.uber.org/zap/CHANGELOG.md
@@ -0,0 +1,305 @@
+# Changelog
+
+## v1.9.1 (06 Aug 2018)
+
+Bugfixes:
+
+* [#614][]: MapObjectEncoder should not ignore empty slices.
+
+## v1.9.0 (19 Jul 2018)
+
+Enhancements:
+* [#602][]: Reduce number of allocations when logging with reflection.
+* [#572][], [#606][]: Expose a registry for third-party logging sinks.
+
+Thanks to @nfarah86, @AlekSi, @JeanMertz, @philippgille, @etsangsplk, and
+@dimroc for their contributions to this release.
+
+## v1.8.0 (13 Apr 2018)
+
+Enhancements:
+* [#508][]: Make log level configurable when redirecting the standard
+  library's logger.
+* [#518][]: Add a logger that writes to a `*testing.TB`.
+* [#577][]: Add a top-level alias for `zapcore.Field` to clean up GoDoc.
+
+Bugfixes:
+* [#574][]: Add a missing import comment to `go.uber.org/zap/buffer`.
+
+Thanks to @DiSiqueira and @djui for their contributions to this release.
+
+## v1.7.1 (25 Sep 2017)
+
+Bugfixes:
+* [#504][]: Store strings when using AddByteString with the map encoder.
+
+## v1.7.0 (21 Sep 2017)
+
+Enhancements:
+
+* [#487][]: Add `NewStdLogAt`, which extends `NewStdLog` by allowing the user
+  to specify the level of the logged messages.
+
+## v1.6.0 (30 Aug 2017)
+
+Enhancements:
+
+* [#491][]: Omit zap stack frames from stacktraces.
+* [#490][]: Add a `ContextMap` method to observer logs for simpler
+  field validation in tests.
+
+## v1.5.0 (22 Jul 2017)
+
+Enhancements:
+
+* [#460][] and [#470][]: Support errors produced by `go.uber.org/multierr`.
+* [#465][]: Support user-supplied encoders for logger names.
+
+Bugfixes:
+
+* [#477][]: Fix a bug that incorrectly truncated deep stacktraces.
+
+Thanks to @richard-tunein and @pavius for their contributions to this release.
+
+## v1.4.1 (08 Jun 2017)
+
+This release fixes two bugs.
+
+Bugfixes:
+
+* [#435][]: Support a variety of case conventions when unmarshaling levels.
+* [#444][]: Fix a panic in the observer.
+
+## v1.4.0 (12 May 2017)
+
+This release adds a few small features and is fully backward-compatible.
+
+Enhancements:
+
+* [#424][]: Add a `LineEnding` field to `EncoderConfig`, allowing users to
+  override the Unix-style default.
+* [#425][]: Preserve time zones when logging times.
+* [#431][]: Make `zap.AtomicLevel` implement `fmt.Stringer`, which makes a
+  variety of operations a bit simpler.
+
+## v1.3.0 (25 Apr 2017)
+
+This release adds an enhancement to zap's testing helpers as well as the
+ability to marshal an AtomicLevel. It is fully backward-compatible.
+
+Enhancements:
+
+* [#415][]: Add a substring-filtering helper to zap's observer. This is
+  particularly useful when testing the `SugaredLogger`.
+* [#416][]: Make `AtomicLevel` implement `encoding.TextMarshaler`.
+
+## v1.2.0 (13 Apr 2017)
+
+This release adds a gRPC compatibility wrapper. It is fully backward-compatible.
+
+Enhancements:
+
+* [#402][]: Add a `zapgrpc` package that wraps zap's Logger and implements
+  `grpclog.Logger`.
+
+## v1.1.0 (31 Mar 2017)
+
+This release fixes two bugs and adds some enhancements to zap's testing helpers.
+It is fully backward-compatible.
+
+Bugfixes:
+
+* [#385][]: Fix caller path trimming on Windows.
+* [#396][]: Fix a panic when attempting to use non-existent directories with
+  zap's configuration struct.
+
+Enhancements:
+
+* [#386][]: Add filtering helpers to zaptest's observing logger.
+
+Thanks to @moitias for contributing to this release.
+
+## v1.0.0 (14 Mar 2017)
+
+This is zap's first stable release. All exported APIs are now final, and no
+further breaking changes will be made in the 1.x release series. Anyone using a
+semver-aware dependency manager should now pin to `^1`.
+
+Breaking changes:
+
+* [#366][]: Add byte-oriented APIs to encoders to log UTF-8 encoded text without
+  casting from `[]byte` to `string`.
+* [#364][]: To support buffering outputs, add `Sync` methods to `zapcore.Core`,
+  `zap.Logger`, and `zap.SugaredLogger`.
+* [#371][]: Rename the `testutils` package to `zaptest`, which is less likely to
+  clash with other testing helpers.
+
+Bugfixes:
+
+* [#362][]: Make the ISO8601 time formatters fixed-width, which is friendlier
+  for tab-separated console output.
+* [#369][]: Remove the automatic locks in `zapcore.NewCore`, which allows zap to
+  work with concurrency-safe `WriteSyncer` implementations.
+* [#347][]: Stop reporting errors when trying to `fsync` standard out on Linux
+  systems.
+* [#373][]: Report the correct caller from zap's standard library
+  interoperability wrappers.
+
+Enhancements:
+
+* [#348][]: Add a registry allowing third-party encodings to work with zap's
+  built-in `Config`.
+* [#327][]: Make the representation of logger callers configurable (like times,
+  levels, and durations).
+* [#376][]: Allow third-party encoders to use their own buffer pools, which
+  removes the last performance advantage that zap's encoders have over plugins.
+* [#346][]: Add `CombineWriteSyncers`, a convenience function to tee multiple
+  `WriteSyncer`s and lock the result.
+* [#365][]: Make zap's stacktraces compatible with mid-stack inlining (coming in
+  Go 1.9).
+* [#372][]: Export zap's observing logger as `zaptest/observer`. This makes it
+  easier for particularly punctilious users to unit test their application's
+  logging.
+
+Thanks to @suyash, @htrendev, @flisky, @Ulexus, and @skipor for their
+contributions to this release.
+
+## v1.0.0-rc.3 (7 Mar 2017)
+
+This is the third release candidate for zap's stable release. There are no
+breaking changes.
+
+Bugfixes:
+
+* [#339][]: Byte slices passed to `zap.Any` are now correctly treated as binary blobs
+  rather than `[]uint8`.
+
+Enhancements:
+
+* [#307][]: Users can opt into colored output for log levels.
+* [#353][]: In addition to hijacking the output of the standard library's
+  package-global logging functions, users can now construct a zap-backed
+  `log.Logger` instance.
+* [#311][]: Frames from common runtime functions and some of zap's internal
+  machinery are now omitted from stacktraces.
+
+Thanks to @ansel1 and @suyash for their contributions to this release.
+
+## v1.0.0-rc.2 (21 Feb 2017)
+
+This is the second release candidate for zap's stable release. It includes two
+breaking changes.
+
+Breaking changes:
+
+* [#316][]: Zap's global loggers are now fully concurrency-safe
+  (previously, users had to ensure that `ReplaceGlobals` was called before the
+  loggers were in use). However, they must now be accessed via the `L()` and
+  `S()` functions. Users can update their projects with
+
+  ```
+  gofmt -r "zap.L -> zap.L()" -w .
+  gofmt -r "zap.S -> zap.S()" -w .
+  ```
+* [#309][] and [#317][]: RC1 was mistakenly shipped with invalid
+  JSON and YAML struct tags on all config structs. This release fixes the tags
+  and adds static analysis to prevent similar bugs in the future.
+
+Bugfixes:
+
+* [#321][]: Redirecting the standard library's `log` output now
+  correctly reports the logger's caller.
+
+Enhancements:
+
+* [#325][] and [#333][]: Zap now transparently supports non-standard, rich
+  errors like those produced by `github.com/pkg/errors`.
+* [#326][]: Though `New(nil)` continues to return a no-op logger, `NewNop()` is
+  now preferred. Users can update their projects with `gofmt -r 'zap.New(nil) ->
+  zap.NewNop()' -w .`.
+* [#300][]: Incorrectly importing zap as `github.com/uber-go/zap` now returns a
+  more informative error.
+
+Thanks to @skipor and @chapsuk for their contributions to this release.
+
+## v1.0.0-rc.1 (14 Feb 2017)
+
+This is the first release candidate for zap's stable release. There are multiple
+breaking changes and improvements from the pre-release version. Most notably:
+
+* **Zap's import path is now "go.uber.org/zap"** &mdash; all users will
+  need to update their code.
+* User-facing types and functions remain in the `zap` package. Code relevant
+  largely to extension authors is now in the `zapcore` package.
+* The `zapcore.Core` type makes it easy for third-party packages to use zap's
+  internals but provide a different user-facing API.
+* `Logger` is now a concrete type instead of an interface.
+* A less verbose (though slower) logging API is included by default.
+* Package-global loggers `L` and `S` are included.
+* A human-friendly console encoder is included.
+* A declarative config struct allows common logger configurations to be managed
+  as configuration instead of code.
+* Sampling is more accurate, and doesn't depend on the standard library's shared
+  timer heap.
+
+## v0.1.0-beta.1 (6 Feb 2017)
+
+This is a minor version, tagged to allow users to pin to the pre-1.0 APIs and
+upgrade at their leisure. Since this is the first tagged release, there are no
+backward compatibility concerns and all functionality is new.
+
+Early zap adopters should pin to the 0.1.x minor version until they're ready to
+upgrade to the upcoming stable release.
+
+[#316]: https://github.com/uber-go/zap/pull/316
+[#309]: https://github.com/uber-go/zap/pull/309
+[#317]: https://github.com/uber-go/zap/pull/317
+[#321]: https://github.com/uber-go/zap/pull/321
+[#325]: https://github.com/uber-go/zap/pull/325
+[#333]: https://github.com/uber-go/zap/pull/333
+[#326]: https://github.com/uber-go/zap/pull/326
+[#300]: https://github.com/uber-go/zap/pull/300
+[#339]: https://github.com/uber-go/zap/pull/339
+[#307]: https://github.com/uber-go/zap/pull/307
+[#353]: https://github.com/uber-go/zap/pull/353
+[#311]: https://github.com/uber-go/zap/pull/311
+[#366]: https://github.com/uber-go/zap/pull/366
+[#364]: https://github.com/uber-go/zap/pull/364
+[#371]: https://github.com/uber-go/zap/pull/371
+[#362]: https://github.com/uber-go/zap/pull/362
+[#369]: https://github.com/uber-go/zap/pull/369
+[#347]: https://github.com/uber-go/zap/pull/347
+[#373]: https://github.com/uber-go/zap/pull/373
+[#348]: https://github.com/uber-go/zap/pull/348
+[#327]: https://github.com/uber-go/zap/pull/327
+[#376]: https://github.com/uber-go/zap/pull/376
+[#346]: https://github.com/uber-go/zap/pull/346
+[#365]: https://github.com/uber-go/zap/pull/365
+[#372]: https://github.com/uber-go/zap/pull/372
+[#385]: https://github.com/uber-go/zap/pull/385
+[#396]: https://github.com/uber-go/zap/pull/396
+[#386]: https://github.com/uber-go/zap/pull/386
+[#402]: https://github.com/uber-go/zap/pull/402
+[#415]: https://github.com/uber-go/zap/pull/415
+[#416]: https://github.com/uber-go/zap/pull/416
+[#424]: https://github.com/uber-go/zap/pull/424
+[#425]: https://github.com/uber-go/zap/pull/425
+[#431]: https://github.com/uber-go/zap/pull/431
+[#435]: https://github.com/uber-go/zap/pull/435
+[#444]: https://github.com/uber-go/zap/pull/444
+[#477]: https://github.com/uber-go/zap/pull/477
+[#465]: https://github.com/uber-go/zap/pull/465
+[#460]: https://github.com/uber-go/zap/pull/460
+[#470]: https://github.com/uber-go/zap/pull/470
+[#487]: https://github.com/uber-go/zap/pull/487
+[#490]: https://github.com/uber-go/zap/pull/490
+[#491]: https://github.com/uber-go/zap/pull/491
+[#504]: https://github.com/uber-go/zap/pull/504
+[#508]: https://github.com/uber-go/zap/pull/508
+[#518]: https://github.com/uber-go/zap/pull/518
+[#577]: https://github.com/uber-go/zap/pull/577
+[#574]: https://github.com/uber-go/zap/pull/574
+[#602]: https://github.com/uber-go/zap/pull/602
+[#572]: https://github.com/uber-go/zap/pull/572
+[#606]: https://github.com/uber-go/zap/pull/606
+[#614]: https://github.com/uber-go/zap/pull/614
diff --git a/vendor/go.uber.org/zap/CODE_OF_CONDUCT.md b/vendor/go.uber.org/zap/CODE_OF_CONDUCT.md
new file mode 100644
index 0000000..e327d9a
--- /dev/null
+++ b/vendor/go.uber.org/zap/CODE_OF_CONDUCT.md
@@ -0,0 +1,75 @@
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+In the interest of fostering an open and welcoming environment, we as
+contributors and maintainers pledge to making participation in our project and
+our community a harassment-free experience for everyone, regardless of age,
+body size, disability, ethnicity, gender identity and expression, level of
+experience, nationality, personal appearance, race, religion, or sexual
+identity and orientation.
+
+## Our Standards
+
+Examples of behavior that contributes to creating a positive environment
+include:
+
+* Using welcoming and inclusive language
+* Being respectful of differing viewpoints and experiences
+* Gracefully accepting constructive criticism
+* Focusing on what is best for the community
+* Showing empathy towards other community members
+
+Examples of unacceptable behavior by participants include:
+
+* The use of sexualized language or imagery and unwelcome sexual attention or
+  advances
+* Trolling, insulting/derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or electronic
+  address, without explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+  professional setting
+
+## Our Responsibilities
+
+Project maintainers are responsible for clarifying the standards of acceptable
+behavior and are expected to take appropriate and fair corrective action in
+response to any instances of unacceptable behavior.
+
+Project maintainers have the right and responsibility to remove, edit, or
+reject comments, commits, code, wiki edits, issues, and other contributions
+that are not aligned to this Code of Conduct, or to ban temporarily or
+permanently any contributor for other behaviors that they deem inappropriate,
+threatening, offensive, or harmful.
+
+## Scope
+
+This Code of Conduct applies both within project spaces and in public spaces
+when an individual is representing the project or its community. Examples of
+representing a project or community include using an official project e-mail
+address, posting via an official social media account, or acting as an
+appointed representative at an online or offline event. Representation of a
+project may be further defined and clarified by project maintainers.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported by contacting the project team at oss-conduct@uber.com. The project
+team will review and investigate all complaints, and will respond in a way
+that it deems appropriate to the circumstances. The project team is obligated
+to maintain confidentiality with regard to the reporter of an incident.
+Further details of specific enforcement policies may be posted separately.
+
+Project maintainers who do not follow or enforce the Code of Conduct in good
+faith may face temporary or permanent repercussions as determined by other
+members of the project's leadership.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage],
+version 1.4, available at
+[http://contributor-covenant.org/version/1/4][version].
+
+[homepage]: http://contributor-covenant.org
+[version]: http://contributor-covenant.org/version/1/4/
diff --git a/vendor/go.uber.org/zap/CONTRIBUTING.md b/vendor/go.uber.org/zap/CONTRIBUTING.md
new file mode 100644
index 0000000..9454bba
--- /dev/null
+++ b/vendor/go.uber.org/zap/CONTRIBUTING.md
@@ -0,0 +1,81 @@
+# Contributing
+
+We'd love your help making zap the very best structured logging library in Go!
+
+If you'd like to add new exported APIs, please [open an issue][open-issue]
+describing your proposal &mdash; discussing API changes ahead of time makes
+pull request review much smoother. In your issue, pull request, and any other
+communications, please remember to treat your fellow contributors with
+respect! We take our [code of conduct](CODE_OF_CONDUCT.md) seriously.
+
+Note that you'll need to sign [Uber's Contributor License Agreement][cla]
+before we can accept any of your contributions. If necessary, a bot will remind
+you to accept the CLA when you open your pull request.
+
+## Setup
+
+[Fork][fork], then clone the repository:
+
+```
+mkdir -p $GOPATH/src/go.uber.org
+cd $GOPATH/src/go.uber.org
+git clone git@github.com:your_github_username/zap.git
+cd zap
+git remote add upstream https://github.com/uber-go/zap.git
+git fetch upstream
+```
+
+Install zap's dependencies:
+
+```
+make dependencies
+```
+
+Make sure that the tests and the linters pass:
+
+```
+make test
+make lint
+```
+
+If you're not using the minor version of Go specified in the Makefile's
+`LINTABLE_MINOR_VERSIONS` variable, `make lint` doesn't do anything. This is
+fine, but it means that you'll only discover lint failures after you open your
+pull request.
+
+## Making Changes
+
+Start by creating a new branch for your changes:
+
+```
+cd $GOPATH/src/go.uber.org/zap
+git checkout master
+git fetch upstream
+git rebase upstream/master
+git checkout -b cool_new_feature
+```
+
+Make your changes, then ensure that `make lint` and `make test` still pass. If
+you're satisfied with your changes, push them to your fork.
+
+```
+git push origin cool_new_feature
+```
+
+Then use the GitHub UI to open a pull request.
+
+At this point, you're waiting on us to review your changes. We *try* to respond
+to issues and pull requests within a few business days, and we may suggest some
+improvements or alternatives. Once your changes are approved, one of the
+project maintainers will merge them.
+
+We're much more likely to approve your changes if you:
+
+* Add tests for new functionality.
+* Write a [good commit message][commit-message].
+* Maintain backward compatibility.
+
+[fork]: https://github.com/uber-go/zap/fork
+[open-issue]: https://github.com/uber-go/zap/issues/new
+[cla]: https://cla-assistant.io/uber-go/zap
+[commit-message]: http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html
diff --git a/vendor/go.uber.org/zap/FAQ.md b/vendor/go.uber.org/zap/FAQ.md
new file mode 100644
index 0000000..4256d35
--- /dev/null
+++ b/vendor/go.uber.org/zap/FAQ.md
@@ -0,0 +1,155 @@
+# Frequently Asked Questions
+
+## Design
+
+### Why spend so much effort on logger performance?
+
+Of course, most applications won't notice the impact of a slow logger: they
+already take tens or hundreds of milliseconds for each operation, so an extra
+millisecond doesn't matter.
+
+On the other hand, why *not* make structured logging fast? The `SugaredLogger`
+isn't any harder to use than other logging packages, and the `Logger` makes
+structured logging possible in performance-sensitive contexts. Across a fleet
+of Go microservices, making each application even slightly more efficient adds
+up quickly.
+
+### Why aren't `Logger` and `SugaredLogger` interfaces?
+
+Unlike the familiar `io.Writer` and `http.Handler`, `Logger` and
+`SugaredLogger` interfaces would include *many* methods. As [Rob Pike points
+out][go-proverbs], "The bigger the interface, the weaker the abstraction."
+Interfaces are also rigid &mdash; *any* change requires releasing a new major
+version, since it breaks all third-party implementations.
+
+Making the `Logger` and `SugaredLogger` concrete types doesn't sacrifice much
+abstraction, and it lets us add methods without introducing breaking changes.
+Your applications should define and depend upon an interface that includes
+just the methods you use.
+
+### Why sample application logs?
+
+Applications often experience runs of errors, either because of a bug or
+because of a misbehaving user. Logging errors is usually a good idea, but it
+can easily make this bad situation worse: not only is your application coping
+with a flood of errors, it's also spending extra CPU cycles and I/O logging
+those errors. Since writes are typically serialized, logging limits throughput
+when you need it most.
+
+Sampling fixes this problem by dropping repetitive log entries. Under normal
+conditions, your application writes out every entry. When similar entries are
+logged hundreds or thousands of times each second, though, zap begins dropping
+duplicates to preserve throughput.
+
+### Why do the structured logging APIs take a message in addition to fields?
+
+Subjectively, we find it helpful to accompany structured context with a brief
+description. This isn't critical during development, but it makes debugging
+and operating unfamiliar systems much easier.
+
+More concretely, zap's sampling algorithm uses the message to identify
+duplicate entries. In our experience, this is a practical middle ground
+between random sampling (which often drops the exact entry that you need while
+debugging) and hashing the complete entry (which is prohibitively expensive).
+
+### Why include package-global loggers?
+
+Since so many other logging packages include a global logger, many
+applications aren't designed to accept loggers as explicit parameters.
+Changing function signatures is often a breaking change, so zap includes
+global loggers to simplify migration.
+
+Avoid them where possible.
+
+### Why include dedicated Panic and Fatal log levels?
+
+In general, application code should handle errors gracefully instead of using
+`panic` or `os.Exit`. However, every rule has exceptions, and it's common to
+crash when an error is truly unrecoverable. To avoid losing any information
+&mdash; especially the reason for the crash &mdash; the logger must flush any
+buffered entries before the process exits.
+
+Zap makes this easy by offering `Panic` and `Fatal` logging methods that
+automatically flush before exiting. Of course, this doesn't guarantee that
+logs will never be lost, but it eliminates a common error.
+
+See the discussion in uber-go/zap#207 for more details.
+
+### What's `DPanic`?
+
+`DPanic` stands for "panic in development." In development, it logs at
+`PanicLevel`; otherwise, it logs at `ErrorLevel`. `DPanic` makes it easier to
+catch errors that are theoretically possible, but shouldn't actually happen,
+*without* crashing in production.
+
+If you've ever written code like this, you need `DPanic`:
+
+```go
+if err != nil {
+  panic(fmt.Sprintf("shouldn't ever get here: %v", err))
+}
+```
+
+## Installation
+
+### What does the error `expects import "go.uber.org/zap"` mean?
+
+Either zap was installed incorrectly or you're referencing the wrong package
+name in your code.
+
+Zap's source code happens to be hosted on GitHub, but the [import
+path][import-path] is `go.uber.org/zap`. This gives us, the project
+maintainers, the freedom to move the source code if necessary. However, it
+means that you need to take a little care when installing and using the
+package.
+
+If you follow two simple rules, everything should work: install zap with `go
+get -u go.uber.org/zap`, and always import it in your code with `import
+"go.uber.org/zap"`. Your code shouldn't contain *any* references to
+`github.com/uber-go/zap`.
+
+## Usage
+
+### Does zap support log rotation?
+
+Zap doesn't natively support rotating log files, since we prefer to leave this
+to an external program like `logrotate`.
+
+However, it's easy to integrate a log rotation package like
+[`gopkg.in/natefinch/lumberjack.v2`][lumberjack] as a `zapcore.WriteSyncer`.
+
+```go
+// lumberjack.Logger is already safe for concurrent use, so we don't need to
+// lock it.
+w := zapcore.AddSync(&lumberjack.Logger{
+  Filename:   "/var/log/myapp/foo.log",
+  MaxSize:    500, // megabytes
+  MaxBackups: 3,
+  MaxAge:     28, // days
+})
+core := zapcore.NewCore(
+  zapcore.NewJSONEncoder(zap.NewProductionEncoderConfig()),
+  w,
+  zap.InfoLevel,
+)
+logger := zap.New(core)
+```
+
+## Extensions
+
+We'd love to support every logging need within zap itself, but we're only
+familiar with a handful of log ingestion systems, flag-parsing packages, and
+the like. Rather than merging code that we can't effectively debug and
+support, we'd rather grow an ecosystem of zap extensions.
+
+We're aware of the following extensions, but haven't used them ourselves:
+
+| Package | Integration |
+| --- | --- |
+| `github.com/tchap/zapext` | Sentry, syslog |
+| `github.com/fgrosse/zaptest` | Ginkgo |
+| `github.com/blendle/zapdriver` | Stackdriver |
+
+[go-proverbs]: https://go-proverbs.github.io/
+[import-path]: https://golang.org/cmd/go/#hdr-Remote_import_paths
+[lumberjack]: https://godoc.org/gopkg.in/natefinch/lumberjack.v2
diff --git a/vendor/go.uber.org/zap/LICENSE.txt b/vendor/go.uber.org/zap/LICENSE.txt
new file mode 100644
index 0000000..6652bed
--- /dev/null
+++ b/vendor/go.uber.org/zap/LICENSE.txt
@@ -0,0 +1,19 @@
+Copyright (c) 2016-2017 Uber Technologies, Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
diff --git a/vendor/go.uber.org/zap/Makefile b/vendor/go.uber.org/zap/Makefile
new file mode 100644
index 0000000..ef7893b
--- /dev/null
+++ b/vendor/go.uber.org/zap/Makefile
@@ -0,0 +1,76 @@
+export GO15VENDOREXPERIMENT=1
+
+BENCH_FLAGS ?= -cpuprofile=cpu.pprof -memprofile=mem.pprof -benchmem
+PKGS ?= $(shell glide novendor)
+# Many Go tools take file globs or directories as arguments instead of packages.
+PKG_FILES ?= *.go zapcore benchmarks buffer zapgrpc zaptest zaptest/observer internal/bufferpool internal/exit internal/color internal/ztest
+
+# The linting tools evolve with each Go version, so run them only on the latest
+# stable release.
+GO_VERSION := $(shell go version | cut -d " " -f 3)
+GO_MINOR_VERSION := $(word 2,$(subst ., ,$(GO_VERSION)))
+LINTABLE_MINOR_VERSIONS := 10
+ifneq ($(filter $(LINTABLE_MINOR_VERSIONS),$(GO_MINOR_VERSION)),)
+SHOULD_LINT := true
+endif
+
+
+.PHONY: all
+all: lint test
+
+.PHONY: dependencies
+dependencies:
+	@echo "Installing Glide and locked dependencies..."
+	glide --version || go get -u -f github.com/Masterminds/glide
+	glide install
+	@echo "Installing test dependencies..."
+	go install ./vendor/github.com/axw/gocov/gocov
+	go install ./vendor/github.com/mattn/goveralls
+ifdef SHOULD_LINT
+	@echo "Installing golint..."
+	go install ./vendor/github.com/golang/lint/golint
+else
+	@echo "Not installing golint, since we don't expect to lint on" $(GO_VERSION)
+endif
+
+# Disable printf-like invocation checking due to testify.assert.Error()
+VET_RULES := -printf=false
+
+.PHONY: lint
+lint:
+ifdef SHOULD_LINT
+	@rm -rf lint.log
+	@echo "Checking formatting..."
+	@gofmt -d -s $(PKG_FILES) 2>&1 | tee lint.log
+	@echo "Installing test dependencies for vet..."
+	@go test -i $(PKGS)
+	@echo "Checking vet..."
+	@$(foreach dir,$(PKG_FILES),go tool vet $(VET_RULES) $(dir) 2>&1 | tee -a lint.log;)
+	@echo "Checking lint..."
+	@$(foreach dir,$(PKGS),golint $(dir) 2>&1 | tee -a lint.log;)
+	@echo "Checking for unresolved FIXMEs..."
+	@git grep -i fixme | grep -v -e vendor -e Makefile | tee -a lint.log
+	@echo "Checking for license headers..."
+	@./check_license.sh | tee -a lint.log
+	@[ ! -s lint.log ]
+else
+	@echo "Skipping linters on" $(GO_VERSION)
+endif
+
+.PHONY: test
+test:
+	go test -race $(PKGS)
+
+.PHONY: cover
+cover:
+	./scripts/cover.sh $(PKGS)
+
+.PHONY: bench
+BENCH ?= .
+bench:
+	@$(foreach pkg,$(PKGS),go test -bench=$(BENCH) -run="^$$" $(BENCH_FLAGS) $(pkg);)
+
+.PHONY: updatereadme
+updatereadme:
+	rm -f README.md
+	cat .readme.tmpl | go run internal/readme/readme.go > README.md
diff --git a/vendor/go.uber.org/zap/README.md b/vendor/go.uber.org/zap/README.md
new file mode 100644
index 0000000..f4fd1cb
--- /dev/null
+++ b/vendor/go.uber.org/zap/README.md
@@ -0,0 +1,136 @@
+# :zap: zap [![GoDoc][doc-img]][doc] [![Build Status][ci-img]][ci] [![Coverage Status][cov-img]][cov]
+
+Blazing fast, structured, leveled logging in Go.
+
+## Installation
+
+`go get -u go.uber.org/zap`
+
+Note that zap only supports the two most recent minor versions of Go.
+
+## Quick Start
+
+In contexts where performance is nice, but not critical, use the
+`SugaredLogger`. It's 4-10x faster than other structured logging
+packages and includes both structured and `printf`-style APIs.
+
+```go
+logger, _ := zap.NewProduction()
+defer logger.Sync() // flushes buffer, if any
+sugar := logger.Sugar()
+sugar.Infow("failed to fetch URL",
+  // Structured context as loosely typed key-value pairs.
+  "url", url,
+  "attempt", 3,
+  "backoff", time.Second,
+)
+sugar.Infof("Failed to fetch URL: %s", url)
+```
+
+When performance and type safety are critical, use the `Logger`. It's even
+faster than the `SugaredLogger` and allocates far less, but it only supports
+structured logging.
+
+```go
+logger, _ := zap.NewProduction()
+defer logger.Sync()
+logger.Info("failed to fetch URL",
+  // Structured context as strongly typed Field values.
+  zap.String("url", url),
+  zap.Int("attempt", 3),
+  zap.Duration("backoff", time.Second),
+)
+```
+
+See the [documentation][doc] and [FAQ](FAQ.md) for more details.
+
+## Performance
+
+For applications that log in the hot path, reflection-based serialization and
+string formatting are prohibitively expensive &mdash; they're CPU-intensive
+and make many small allocations. Put differently, using `encoding/json` and
+`fmt.Fprintf` to log tons of `interface{}`s makes your application slow.
+
+Zap takes a different approach. It includes a reflection-free, zero-allocation
+JSON encoder, and the base `Logger` strives to avoid serialization overhead
+and allocations wherever possible. By building the high-level `SugaredLogger`
+on that foundation, zap lets users *choose* when they need to count every
+allocation and when they'd prefer a more familiar, loosely typed API.
+
+As measured by its own [benchmarking suite][], not only is zap more performant
+than comparable structured logging packages &mdash; it's also faster than the
+standard library. Like all benchmarks, take these with a grain of salt.<sup
+id="anchor-versions">[1](#footnote-versions)</sup>
+
+Log a message and 10 fields:
+
+| Package | Time | Objects Allocated |
+| :--- | :---: | :---: |
+| :zap: zap | 3131 ns/op | 5 allocs/op |
+| :zap: zap (sugared) | 4173 ns/op | 21 allocs/op |
+| zerolog | 16154 ns/op | 90 allocs/op |
+| lion | 16341 ns/op | 111 allocs/op |
+| go-kit | 17049 ns/op | 126 allocs/op |
+| logrus | 23662 ns/op | 142 allocs/op |
+| log15 | 36351 ns/op | 149 allocs/op |
+| apex/log | 42530 ns/op | 126 allocs/op |
+
+Log a message with a logger that already has 10 fields of context:
+
+| Package | Time | Objects Allocated |
+| :--- | :---: | :---: |
+| :zap: zap | 380 ns/op | 0 allocs/op |
+| :zap: zap (sugared) | 564 ns/op | 2 allocs/op |
+| zerolog | 321 ns/op | 0 allocs/op |
+| lion | 7092 ns/op | 39 allocs/op |
+| go-kit | 20226 ns/op | 115 allocs/op |
+| logrus | 22312 ns/op | 130 allocs/op |
+| log15 | 28788 ns/op | 79 allocs/op |
+| apex/log | 42063 ns/op | 115 allocs/op |
+
+Log a static string, without any context or `printf`-style templating:
+
+| Package | Time | Objects Allocated |
+| :--- | :---: | :---: |
+| :zap: zap | 361 ns/op | 0 allocs/op |
+| :zap: zap (sugared) | 534 ns/op | 2 allocs/op |
+| zerolog | 323 ns/op | 0 allocs/op |
+| standard library | 575 ns/op | 2 allocs/op |
+| go-kit | 922 ns/op | 13 allocs/op |
+| lion | 1413 ns/op | 10 allocs/op |
+| logrus | 2291 ns/op | 27 allocs/op |
+| apex/log | 3690 ns/op | 11 allocs/op |
+| log15 | 5954 ns/op | 26 allocs/op |
+
+## Development Status: Stable
+
+All APIs are finalized, and no breaking changes will be made in the 1.x series
+of releases. Users of semver-aware dependency management systems should pin
+zap to `^1`.
+
+## Contributing
+
+We encourage and support an active, healthy community of contributors &mdash;
+including you! Details are in the [contribution guide](CONTRIBUTING.md) and
+the [code of conduct](CODE_OF_CONDUCT.md). The zap maintainers keep an eye on
+issues and pull requests, but you can also report any negative conduct to
+oss-conduct@uber.com. That email list is a private, safe space; even the zap
+maintainers don't have access, so don't hesitate to hold us to a high
+standard.
+
+<hr>
+
+Released under the [MIT License](LICENSE.txt).
+
+<sup id="footnote-versions">1</sup> In particular, keep in mind that we may be
+benchmarking against slightly older versions of other packages. Versions are
+pinned in zap's [glide.lock][] file. [↩](#anchor-versions)
+
+[doc-img]: https://godoc.org/go.uber.org/zap?status.svg
+[doc]: https://godoc.org/go.uber.org/zap
+[ci-img]: https://travis-ci.org/uber-go/zap.svg?branch=master
+[ci]: https://travis-ci.org/uber-go/zap
+[cov-img]: https://codecov.io/gh/uber-go/zap/branch/master/graph/badge.svg
+[cov]: https://codecov.io/gh/uber-go/zap
+[benchmarking suite]: https://github.com/uber-go/zap/tree/master/benchmarks
+[glide.lock]: https://github.com/uber-go/zap/blob/master/glide.lock
diff --git a/vendor/go.uber.org/zap/array.go b/vendor/go.uber.org/zap/array.go
new file mode 100644
index 0000000..5be3704
--- /dev/null
+++ b/vendor/go.uber.org/zap/array.go
@@ -0,0 +1,320 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zap
+
+import (
+	"time"
+
+	"go.uber.org/zap/zapcore"
+)
+
+// Array constructs a field with the given key and ArrayMarshaler. It provides
+// a flexible, but still type-safe and efficient, way to add array-like types
+// to the logging context. The struct's MarshalLogArray method is called lazily.
+func Array(key string, val zapcore.ArrayMarshaler) Field {
+	return Field{Key: key, Type: zapcore.ArrayMarshalerType, Interface: val}
+}
+
+// Bools constructs a field that carries a slice of bools.
+func Bools(key string, bs []bool) Field {
+	return Array(key, bools(bs))
+}
+
+// ByteStrings constructs a field that carries a slice of []byte, each of which
+// must be UTF-8 encoded text.
+func ByteStrings(key string, bss [][]byte) Field {
+	return Array(key, byteStringsArray(bss))
+}
+
+// Complex128s constructs a field that carries a slice of complex numbers.
+func Complex128s(key string, nums []complex128) Field {
+	return Array(key, complex128s(nums))
+}
+
+// Complex64s constructs a field that carries a slice of complex numbers.
+func Complex64s(key string, nums []complex64) Field {
+	return Array(key, complex64s(nums))
+}
+
+// Durations constructs a field that carries a slice of time.Durations.
+func Durations(key string, ds []time.Duration) Field {
+	return Array(key, durations(ds))
+}
+
+// Float64s constructs a field that carries a slice of floats.
+func Float64s(key string, nums []float64) Field {
+	return Array(key, float64s(nums))
+}
+
+// Float32s constructs a field that carries a slice of floats.
+func Float32s(key string, nums []float32) Field {
+	return Array(key, float32s(nums))
+}
+
+// Ints constructs a field that carries a slice of integers.
+func Ints(key string, nums []int) Field {
+	return Array(key, ints(nums))
+}
+
+// Int64s constructs a field that carries a slice of integers.
+func Int64s(key string, nums []int64) Field {
+	return Array(key, int64s(nums))
+}
+
+// Int32s constructs a field that carries a slice of integers.
+func Int32s(key string, nums []int32) Field {
+	return Array(key, int32s(nums))
+}
+
+// Int16s constructs a field that carries a slice of integers.
+func Int16s(key string, nums []int16) Field {
+	return Array(key, int16s(nums))
+}
+
+// Int8s constructs a field that carries a slice of integers.
+func Int8s(key string, nums []int8) Field {
+	return Array(key, int8s(nums))
+}
+
+// Strings constructs a field that carries a slice of strings.
+func Strings(key string, ss []string) Field {
+	return Array(key, stringArray(ss))
+}
+
+// Times constructs a field that carries a slice of time.Times.
+func Times(key string, ts []time.Time) Field {
+	return Array(key, times(ts))
+}
+
+// Uints constructs a field that carries a slice of unsigned integers.
+func Uints(key string, nums []uint) Field {
+	return Array(key, uints(nums))
+}
+
+// Uint64s constructs a field that carries a slice of unsigned integers.
+func Uint64s(key string, nums []uint64) Field {
+	return Array(key, uint64s(nums))
+}
+
+// Uint32s constructs a field that carries a slice of unsigned integers.
+func Uint32s(key string, nums []uint32) Field {
+	return Array(key, uint32s(nums))
+}
+
+// Uint16s constructs a field that carries a slice of unsigned integers.
+func Uint16s(key string, nums []uint16) Field {
+	return Array(key, uint16s(nums))
+}
+
+// Uint8s constructs a field that carries a slice of unsigned integers.
+func Uint8s(key string, nums []uint8) Field {
+	return Array(key, uint8s(nums))
+}
+
+// Uintptrs constructs a field that carries a slice of pointer addresses.
+func Uintptrs(key string, us []uintptr) Field {
+	return Array(key, uintptrs(us))
+}
+
+// Errors constructs a field that carries a slice of errors.
+func Errors(key string, errs []error) Field {
+	return Array(key, errArray(errs))
+}
+
+type bools []bool
+
+func (bs bools) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range bs {
+		arr.AppendBool(bs[i])
+	}
+	return nil
+}
+
+type byteStringsArray [][]byte
+
+func (bss byteStringsArray) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range bss {
+		arr.AppendByteString(bss[i])
+	}
+	return nil
+}
+
+type complex128s []complex128
+
+func (nums complex128s) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range nums {
+		arr.AppendComplex128(nums[i])
+	}
+	return nil
+}
+
+type complex64s []complex64
+
+func (nums complex64s) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range nums {
+		arr.AppendComplex64(nums[i])
+	}
+	return nil
+}
+
+type durations []time.Duration
+
+func (ds durations) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range ds {
+		arr.AppendDuration(ds[i])
+	}
+	return nil
+}
+
+type float64s []float64
+
+func (nums float64s) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range nums {
+		arr.AppendFloat64(nums[i])
+	}
+	return nil
+}
+
+type float32s []float32
+
+func (nums float32s) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range nums {
+		arr.AppendFloat32(nums[i])
+	}
+	return nil
+}
+
+type ints []int
+
+func (nums ints) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range nums {
+		arr.AppendInt(nums[i])
+	}
+	return nil
+}
+
+type int64s []int64
+
+func (nums int64s) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range nums {
+		arr.AppendInt64(nums[i])
+	}
+	return nil
+}
+
+type int32s []int32
+
+func (nums int32s) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range nums {
+		arr.AppendInt32(nums[i])
+	}
+	return nil
+}
+
+type int16s []int16
+
+func (nums int16s) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range nums {
+		arr.AppendInt16(nums[i])
+	}
+	return nil
+}
+
+type int8s []int8
+
+func (nums int8s) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range nums {
+		arr.AppendInt8(nums[i])
+	}
+	return nil
+}
+
+type stringArray []string
+
+func (ss stringArray) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range ss {
+		arr.AppendString(ss[i])
+	}
+	return nil
+}
+
+type times []time.Time
+
+func (ts times) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range ts {
+		arr.AppendTime(ts[i])
+	}
+	return nil
+}
+
+type uints []uint
+
+func (nums uints) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range nums {
+		arr.AppendUint(nums[i])
+	}
+	return nil
+}
+
+type uint64s []uint64
+
+func (nums uint64s) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range nums {
+		arr.AppendUint64(nums[i])
+	}
+	return nil
+}
+
+type uint32s []uint32
+
+func (nums uint32s) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range nums {
+		arr.AppendUint32(nums[i])
+	}
+	return nil
+}
+
+type uint16s []uint16
+
+func (nums uint16s) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range nums {
+		arr.AppendUint16(nums[i])
+	}
+	return nil
+}
+
+type uint8s []uint8
+
+func (nums uint8s) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range nums {
+		arr.AppendUint8(nums[i])
+	}
+	return nil
+}
+
+type uintptrs []uintptr
+
+func (nums uintptrs) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range nums {
+		arr.AppendUintptr(nums[i])
+	}
+	return nil
+}
diff --git a/vendor/go.uber.org/zap/buffer/buffer.go b/vendor/go.uber.org/zap/buffer/buffer.go
new file mode 100644
index 0000000..7592e8c
--- /dev/null
+++ b/vendor/go.uber.org/zap/buffer/buffer.go
@@ -0,0 +1,115 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+// Package buffer provides a thin wrapper around a byte slice. Unlike the
+// standard library's bytes.Buffer, it supports a portion of the strconv
+// package's zero-allocation formatters.
+package buffer // import "go.uber.org/zap/buffer"
+
+import "strconv"
+
+const _size = 1024 // by default, create 1 KiB buffers
+
+// Buffer is a thin wrapper around a byte slice. It's intended to be pooled, so
+// the only way to construct one is via a Pool.
+type Buffer struct {
+	bs   []byte
+	pool Pool
+}
+
+// AppendByte writes a single byte to the Buffer.
+func (b *Buffer) AppendByte(v byte) {
+	b.bs = append(b.bs, v)
+}
+
+// AppendString writes a string to the Buffer.
+func (b *Buffer) AppendString(s string) {
+	b.bs = append(b.bs, s...)
+}
+
+// AppendInt appends an integer to the underlying buffer (assuming base 10).
+func (b *Buffer) AppendInt(i int64) {
+	b.bs = strconv.AppendInt(b.bs, i, 10)
+}
+
+// AppendUint appends an unsigned integer to the underlying buffer (assuming
+// base 10).
+func (b *Buffer) AppendUint(i uint64) {
+	b.bs = strconv.AppendUint(b.bs, i, 10)
+}
+
+// AppendBool appends a bool to the underlying buffer.
+func (b *Buffer) AppendBool(v bool) {
+	b.bs = strconv.AppendBool(b.bs, v)
+}
+
+// AppendFloat appends a float to the underlying buffer. It doesn't quote NaN
+// or +/- Inf.
+func (b *Buffer) AppendFloat(f float64, bitSize int) {
+	b.bs = strconv.AppendFloat(b.bs, f, 'f', -1, bitSize)
+}
+
+// Len returns the length of the underlying byte slice.
+func (b *Buffer) Len() int {
+	return len(b.bs)
+}
+
+// Cap returns the capacity of the underlying byte slice.
+func (b *Buffer) Cap() int {
+	return cap(b.bs)
+}
+
+// Bytes returns a mutable reference to the underlying byte slice.
+func (b *Buffer) Bytes() []byte {
+	return b.bs
+}
+
+// String returns a string copy of the underlying byte slice.
+func (b *Buffer) String() string {
+	return string(b.bs)
+}
+
+// Reset resets the underlying byte slice. Subsequent writes re-use the slice's
+// backing array.
+func (b *Buffer) Reset() {
+	b.bs = b.bs[:0]
+}
+
+// Write implements io.Writer.
+func (b *Buffer) Write(bs []byte) (int, error) {
+	b.bs = append(b.bs, bs...)
+	return len(bs), nil
+}
+
+// TrimNewline trims any final "\n" byte from the end of the buffer.
+func (b *Buffer) TrimNewline() {
+	if i := len(b.bs) - 1; i >= 0 {
+		if b.bs[i] == '\n' {
+			b.bs = b.bs[:i]
+		}
+	}
+}
+
+// Free returns the Buffer to its Pool.
+//
+// Callers must not retain references to the Buffer after calling Free.
+func (b *Buffer) Free() {
+	b.pool.put(b)
+}
diff --git a/vendor/go.uber.org/zap/buffer/pool.go b/vendor/go.uber.org/zap/buffer/pool.go
new file mode 100644
index 0000000..8fb3e20
--- /dev/null
+++ b/vendor/go.uber.org/zap/buffer/pool.go
@@ -0,0 +1,49 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package buffer
+
+import "sync"
+
+// A Pool is a type-safe wrapper around a sync.Pool.
+type Pool struct {
+	p *sync.Pool
+}
+
+// NewPool constructs a new Pool.
+func NewPool() Pool {
+	return Pool{p: &sync.Pool{
+		New: func() interface{} {
+			return &Buffer{bs: make([]byte, 0, _size)}
+		},
+	}}
+}
+
+// Get retrieves a Buffer from the pool, creating one if necessary.
+func (p Pool) Get() *Buffer {
+	buf := p.p.Get().(*Buffer)
+	buf.Reset()
+	buf.pool = p
+	return buf
+}
+
+func (p Pool) put(buf *Buffer) {
+	p.p.Put(buf)
+}
diff --git a/vendor/go.uber.org/zap/check_license.sh b/vendor/go.uber.org/zap/check_license.sh
new file mode 100755
index 0000000..345ac8b
--- /dev/null
+++ b/vendor/go.uber.org/zap/check_license.sh
@@ -0,0 +1,17 @@
+#!/bin/bash -e
+
+ERROR_COUNT=0
+while read -r file
+do
+	case "$(head -1 "${file}")" in
+		*"Copyright (c) "*" Uber Technologies, Inc.")
+			# everything's cool
+			;;
+		*)
+			echo "$file is missing license header."
+			(( ERROR_COUNT++ ))
+			;;
+	esac
+done < <(git ls-files "*\.go")
+
+exit $ERROR_COUNT
diff --git a/vendor/go.uber.org/zap/config.go b/vendor/go.uber.org/zap/config.go
new file mode 100644
index 0000000..6fe17d9
--- /dev/null
+++ b/vendor/go.uber.org/zap/config.go
@@ -0,0 +1,243 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zap
+
+import (
+	"sort"
+	"time"
+
+	"go.uber.org/zap/zapcore"
+)
+
+// SamplingConfig sets a sampling strategy for the logger. Sampling caps the
+// global CPU and I/O load that logging puts on your process while attempting
+// to preserve a representative subset of your logs.
+//
+// Values configured here are per-second. See zapcore.NewSampler for details.
+type SamplingConfig struct {
+	Initial    int `json:"initial" yaml:"initial"`
+	Thereafter int `json:"thereafter" yaml:"thereafter"`
+}
+
+// Config offers a declarative way to construct a logger. It doesn't do
+// anything that can't be done with New, Options, and the various
+// zapcore.WriteSyncer and zapcore.Core wrappers, but it's a simpler way to
+// toggle common options.
+//
+// Note that Config intentionally supports only the most common options. More
+// unusual logging setups (logging to network connections or message queues,
+// splitting output between multiple files, etc.) are possible, but require
+// direct use of the zapcore package. For sample code, see the package-level
+// BasicConfiguration and AdvancedConfiguration examples.
+//
+// For an example showing runtime log level changes, see the documentation for
+// AtomicLevel.
+type Config struct {
+	// Level is the minimum enabled logging level. Note that this is a dynamic
+	// level, so calling Config.Level.SetLevel will atomically change the log
+	// level of all loggers descended from this config.
+	Level AtomicLevel `json:"level" yaml:"level"`
+	// Development puts the logger in development mode, which changes the
+	// behavior of DPanicLevel and takes stacktraces more liberally.
+	Development bool `json:"development" yaml:"development"`
+	// DisableCaller stops annotating logs with the calling function's file
+	// name and line number. By default, all logs are annotated.
+	DisableCaller bool `json:"disableCaller" yaml:"disableCaller"`
+	// DisableStacktrace completely disables automatic stacktrace capturing. By
+	// default, stacktraces are captured for WarnLevel and above logs in
+	// development and ErrorLevel and above in production.
+	DisableStacktrace bool `json:"disableStacktrace" yaml:"disableStacktrace"`
+	// Sampling sets a sampling policy. A nil SamplingConfig disables sampling.
+	Sampling *SamplingConfig `json:"sampling" yaml:"sampling"`
+	// Encoding sets the logger's encoding. Valid values are "json" and
+	// "console", as well as any third-party encodings registered via
+	// RegisterEncoder.
+	Encoding string `json:"encoding" yaml:"encoding"`
+	// EncoderConfig sets options for the chosen encoder. See
+	// zapcore.EncoderConfig for details.
+	EncoderConfig zapcore.EncoderConfig `json:"encoderConfig" yaml:"encoderConfig"`
+	// OutputPaths is a list of URLs or file paths to write logging output to.
+	// See Open for details.
+	OutputPaths []string `json:"outputPaths" yaml:"outputPaths"`
+	// ErrorOutputPaths is a list of URLs to write internal logger errors to.
+	// The default is standard error.
+	//
+	// Note that this setting only affects internal errors; for sample code that
+	// sends error-level logs to a different location from info- and debug-level
+	// logs, see the package-level AdvancedConfiguration example.
+	ErrorOutputPaths []string `json:"errorOutputPaths" yaml:"errorOutputPaths"`
+	// InitialFields is a collection of fields to add to the root logger.
+	InitialFields map[string]interface{} `json:"initialFields" yaml:"initialFields"`
+}
+
+// NewProductionEncoderConfig returns an opinionated EncoderConfig for
+// production environments.
+func NewProductionEncoderConfig() zapcore.EncoderConfig {
+	return zapcore.EncoderConfig{
+		TimeKey:        "ts",
+		LevelKey:       "level",
+		NameKey:        "logger",
+		CallerKey:      "caller",
+		MessageKey:     "msg",
+		StacktraceKey:  "stacktrace",
+		LineEnding:     zapcore.DefaultLineEnding,
+		EncodeLevel:    zapcore.LowercaseLevelEncoder,
+		EncodeTime:     zapcore.EpochTimeEncoder,
+		EncodeDuration: zapcore.SecondsDurationEncoder,
+		EncodeCaller:   zapcore.ShortCallerEncoder,
+	}
+}
+
+// NewProductionConfig is a reasonable production logging configuration.
+// Logging is enabled at InfoLevel and above.
+//
+// It uses a JSON encoder, writes to standard error, and enables sampling.
+// Stacktraces are automatically included on logs of ErrorLevel and above.
+func NewProductionConfig() Config {
+	return Config{
+		Level:       NewAtomicLevelAt(InfoLevel),
+		Development: false,
+		Sampling: &SamplingConfig{
+			Initial:    100,
+			Thereafter: 100,
+		},
+		Encoding:         "json",
+		EncoderConfig:    NewProductionEncoderConfig(),
+		OutputPaths:      []string{"stderr"},
+		ErrorOutputPaths: []string{"stderr"},
+	}
+}
+
+// NewDevelopmentEncoderConfig returns an opinionated EncoderConfig for
+// development environments.
+func NewDevelopmentEncoderConfig() zapcore.EncoderConfig {
+	return zapcore.EncoderConfig{
+		// Keys can be anything except the empty string.
+		TimeKey:        "T",
+		LevelKey:       "L",
+		NameKey:        "N",
+		CallerKey:      "C",
+		MessageKey:     "M",
+		StacktraceKey:  "S",
+		LineEnding:     zapcore.DefaultLineEnding,
+		EncodeLevel:    zapcore.CapitalLevelEncoder,
+		EncodeTime:     zapcore.ISO8601TimeEncoder,
+		EncodeDuration: zapcore.StringDurationEncoder,
+		EncodeCaller:   zapcore.ShortCallerEncoder,
+	}
+}
+
+// NewDevelopmentConfig is a reasonable development logging configuration.
+// Logging is enabled at DebugLevel and above.
+//
+// It enables development mode (which makes DPanicLevel logs panic), uses a
+// console encoder, writes to standard error, and disables sampling.
+// Stacktraces are automatically included on logs of WarnLevel and above.
+func NewDevelopmentConfig() Config {
+	return Config{
+		Level:            NewAtomicLevelAt(DebugLevel),
+		Development:      true,
+		Encoding:         "console",
+		EncoderConfig:    NewDevelopmentEncoderConfig(),
+		OutputPaths:      []string{"stderr"},
+		ErrorOutputPaths: []string{"stderr"},
+	}
+}
+
+// Build constructs a logger from the Config and Options.
+func (cfg Config) Build(opts ...Option) (*Logger, error) {
+	enc, err := cfg.buildEncoder()
+	if err != nil {
+		return nil, err
+	}
+
+	sink, errSink, err := cfg.openSinks()
+	if err != nil {
+		return nil, err
+	}
+
+	log := New(
+		zapcore.NewCore(enc, sink, cfg.Level),
+		cfg.buildOptions(errSink)...,
+	)
+	if len(opts) > 0 {
+		log = log.WithOptions(opts...)
+	}
+	return log, nil
+}
+
+func (cfg Config) buildOptions(errSink zapcore.WriteSyncer) []Option {
+	opts := []Option{ErrorOutput(errSink)}
+
+	if cfg.Development {
+		opts = append(opts, Development())
+	}
+
+	if !cfg.DisableCaller {
+		opts = append(opts, AddCaller())
+	}
+
+	stackLevel := ErrorLevel
+	if cfg.Development {
+		stackLevel = WarnLevel
+	}
+	if !cfg.DisableStacktrace {
+		opts = append(opts, AddStacktrace(stackLevel))
+	}
+
+	if cfg.Sampling != nil {
+		opts = append(opts, WrapCore(func(core zapcore.Core) zapcore.Core {
+			return zapcore.NewSampler(core, time.Second, int(cfg.Sampling.Initial), int(cfg.Sampling.Thereafter))
+		}))
+	}
+
+	if len(cfg.InitialFields) > 0 {
+		fs := make([]Field, 0, len(cfg.InitialFields))
+		keys := make([]string, 0, len(cfg.InitialFields))
+		for k := range cfg.InitialFields {
+			keys = append(keys, k)
+		}
+		sort.Strings(keys)
+		for _, k := range keys {
+			fs = append(fs, Any(k, cfg.InitialFields[k]))
+		}
+		opts = append(opts, Fields(fs...))
+	}
+
+	return opts
+}
+
+func (cfg Config) openSinks() (zapcore.WriteSyncer, zapcore.WriteSyncer, error) {
+	sink, closeOut, err := Open(cfg.OutputPaths...)
+	if err != nil {
+		return nil, nil, err
+	}
+	errSink, _, err := Open(cfg.ErrorOutputPaths...)
+	if err != nil {
+		closeOut()
+		return nil, nil, err
+	}
+	return sink, errSink, nil
+}
+
+func (cfg Config) buildEncoder() (zapcore.Encoder, error) {
+	return newEncoder(cfg.Encoding, cfg.EncoderConfig)
+}
diff --git a/vendor/go.uber.org/zap/doc.go b/vendor/go.uber.org/zap/doc.go
new file mode 100644
index 0000000..8638dd1
--- /dev/null
+++ b/vendor/go.uber.org/zap/doc.go
@@ -0,0 +1,113 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+// Package zap provides fast, structured, leveled logging.
+//
+// For applications that log in the hot path, reflection-based serialization
+// and string formatting are prohibitively expensive - they're CPU-intensive
+// and make many small allocations. Put differently, using json.Marshal and
+// fmt.Fprintf to log tons of interface{} makes your application slow.
+//
+// Zap takes a different approach. It includes a reflection-free,
+// zero-allocation JSON encoder, and the base Logger strives to avoid
+// serialization overhead and allocations wherever possible. By building the
+// high-level SugaredLogger on that foundation, zap lets users choose when
+// they need to count every allocation and when they'd prefer a more familiar,
+// loosely typed API.
+//
+// Choosing a Logger
+//
+// In contexts where performance is nice, but not critical, use the
+// SugaredLogger. It's 4-10x faster than other structured logging packages and
+// supports both structured and printf-style logging. Like log15 and go-kit,
+// the SugaredLogger's structured logging APIs are loosely typed and accept a
+// variadic number of key-value pairs. (For more advanced use cases, they also
+// accept strongly typed fields - see the SugaredLogger.With documentation for
+// details.)
+//  sugar := zap.NewExample().Sugar()
+//  defer sugar.Sync()
+//  sugar.Infow("failed to fetch URL",
+//    "url", "http://example.com",
+//    "attempt", 3,
+//    "backoff", time.Second,
+//  )
+//  sugar.Infof("failed to fetch URL: %s", "http://example.com")
+//
+// By default, loggers are unbuffered. However, since zap's low-level APIs
+// allow buffering, calling Sync before letting your process exit is a good
+// habit.
+//
+// In the rare contexts where every microsecond and every allocation matter,
+// use the Logger. It's even faster than the SugaredLogger and allocates far
+// less, but it only supports strongly-typed, structured logging.
+//  logger := zap.NewExample()
+//  defer logger.Sync()
+//  logger.Info("failed to fetch URL",
+//    zap.String("url", "http://example.com"),
+//    zap.Int("attempt", 3),
+//    zap.Duration("backoff", time.Second),
+//  )
+//
+// Choosing between the Logger and SugaredLogger doesn't need to be an
+// application-wide decision: converting between the two is simple and
+// inexpensive.
+//   logger := zap.NewExample()
+//   defer logger.Sync()
+//   sugar := logger.Sugar()
+//   plain := sugar.Desugar()
+//
+// Configuring Zap
+//
+// The simplest way to build a Logger is to use zap's opinionated presets:
+// NewExample, NewProduction, and NewDevelopment. These presets build a logger
+// with a single function call:
+//  logger, err := zap.NewProduction()
+//  if err != nil {
+//    log.Fatalf("can't initialize zap logger: %v", err)
+//  }
+//  defer logger.Sync()
+//
+// Presets are fine for small projects, but larger projects and organizations
+// naturally require a bit more customization. For most users, zap's Config
+// struct strikes the right balance between flexibility and convenience. See
+// the package-level BasicConfiguration example for sample code.
+//
+// More unusual configurations (splitting output between files, sending logs
+// to a message queue, etc.) are possible, but require direct use of
+// go.uber.org/zap/zapcore. See the package-level AdvancedConfiguration
+// example for sample code.
+//
+// Extending Zap
+//
+// The zap package itself is a relatively thin wrapper around the interfaces
+// in go.uber.org/zap/zapcore. Extending zap to support a new encoding (e.g.,
+// BSON), a new log sink (e.g., Kafka), or something more exotic (perhaps an
+// exception aggregation service, like Sentry or Rollbar) typically requires
+// implementing the zapcore.Encoder, zapcore.WriteSyncer, or zapcore.Core
+// interfaces. See the zapcore documentation for details.
+//
+// Similarly, package authors can use the high-performance Encoder and Core
+// implementations in the zapcore package to build their own loggers.
+//
+// Frequently Asked Questions
+//
+// An FAQ covering everything from installation errors to design decisions is
+// available at https://github.com/uber-go/zap/blob/master/FAQ.md.
+package zap // import "go.uber.org/zap"
diff --git a/vendor/go.uber.org/zap/encoder.go b/vendor/go.uber.org/zap/encoder.go
new file mode 100644
index 0000000..2e9d3c3
--- /dev/null
+++ b/vendor/go.uber.org/zap/encoder.go
@@ -0,0 +1,75 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zap
+
+import (
+	"errors"
+	"fmt"
+	"sync"
+
+	"go.uber.org/zap/zapcore"
+)
+
+var (
+	errNoEncoderNameSpecified = errors.New("no encoder name specified")
+
+	_encoderNameToConstructor = map[string]func(zapcore.EncoderConfig) (zapcore.Encoder, error){
+		"console": func(encoderConfig zapcore.EncoderConfig) (zapcore.Encoder, error) {
+			return zapcore.NewConsoleEncoder(encoderConfig), nil
+		},
+		"json": func(encoderConfig zapcore.EncoderConfig) (zapcore.Encoder, error) {
+			return zapcore.NewJSONEncoder(encoderConfig), nil
+		},
+	}
+	_encoderMutex sync.RWMutex
+)
+
+// RegisterEncoder registers an encoder constructor, which the Config struct
+// can then reference. By default, the "json" and "console" encoders are
+// registered.
+//
+// Attempting to register an encoder whose name is already taken returns an
+// error.
+func RegisterEncoder(name string, constructor func(zapcore.EncoderConfig) (zapcore.Encoder, error)) error {
+	_encoderMutex.Lock()
+	defer _encoderMutex.Unlock()
+	if name == "" {
+		return errNoEncoderNameSpecified
+	}
+	if _, ok := _encoderNameToConstructor[name]; ok {
+		return fmt.Errorf("encoder already registered for name %q", name)
+	}
+	_encoderNameToConstructor[name] = constructor
+	return nil
+}
+
+func newEncoder(name string, encoderConfig zapcore.EncoderConfig) (zapcore.Encoder, error) {
+	_encoderMutex.RLock()
+	defer _encoderMutex.RUnlock()
+	if name == "" {
+		return nil, errNoEncoderNameSpecified
+	}
+	constructor, ok := _encoderNameToConstructor[name]
+	if !ok {
+		return nil, fmt.Errorf("no encoder registered for name %q", name)
+	}
+	return constructor(encoderConfig)
+}
diff --git a/vendor/go.uber.org/zap/error.go b/vendor/go.uber.org/zap/error.go
new file mode 100644
index 0000000..65982a5
--- /dev/null
+++ b/vendor/go.uber.org/zap/error.go
@@ -0,0 +1,80 @@
+// Copyright (c) 2017 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zap
+
+import (
+	"sync"
+
+	"go.uber.org/zap/zapcore"
+)
+
+var _errArrayElemPool = sync.Pool{New: func() interface{} {
+	return &errArrayElem{}
+}}
+
+// Error is shorthand for the common idiom NamedError("error", err).
+func Error(err error) Field {
+	return NamedError("error", err)
+}
+
+// NamedError constructs a field that lazily stores err.Error() under the
+// provided key. Errors which also implement fmt.Formatter (like those produced
+// by github.com/pkg/errors) will also have their verbose representation stored
+// under key+"Verbose". If passed a nil error, the field is a no-op.
+//
+// For the common case in which the key is simply "error", the Error function
+// is shorter and less repetitive.
+func NamedError(key string, err error) Field {
+	if err == nil {
+		return Skip()
+	}
+	return Field{Key: key, Type: zapcore.ErrorType, Interface: err}
+}
+
+type errArray []error
+
+func (errs errArray) MarshalLogArray(arr zapcore.ArrayEncoder) error {
+	for i := range errs {
+		if errs[i] == nil {
+			continue
+		}
+		// To represent each error as an object with an "error" attribute and
+		// potentially an "errorVerbose" attribute, we need to wrap it in a
+		// type that implements LogObjectMarshaler. To prevent this from
+		// allocating, pool the wrapper type.
+		elem := _errArrayElemPool.Get().(*errArrayElem)
+		elem.error = errs[i]
+		arr.AppendObject(elem)
+		elem.error = nil
+		_errArrayElemPool.Put(elem)
+	}
+	return nil
+}
+
+type errArrayElem struct {
+	error
+}
+
+func (e *errArrayElem) MarshalLogObject(enc zapcore.ObjectEncoder) error {
+	// Re-use the error field's logic, which supports non-standard error types.
+	Error(e.error).AddTo(enc)
+	return nil
+}
diff --git a/vendor/go.uber.org/zap/field.go b/vendor/go.uber.org/zap/field.go
new file mode 100644
index 0000000..5130e13
--- /dev/null
+++ b/vendor/go.uber.org/zap/field.go
@@ -0,0 +1,310 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zap
+
+import (
+	"fmt"
+	"math"
+	"time"
+
+	"go.uber.org/zap/zapcore"
+)
+
+// Field is an alias for Field. Aliasing this type dramatically
+// improves the navigability of this package's API documentation.
+type Field = zapcore.Field
+
+// Skip constructs a no-op field, which is often useful when handling invalid
+// inputs in other Field constructors.
+func Skip() Field {
+	return Field{Type: zapcore.SkipType}
+}
+
+// Binary constructs a field that carries an opaque binary blob.
+//
+// Binary data is serialized in an encoding-appropriate format. For example,
+// zap's JSON encoder base64-encodes binary blobs. To log UTF-8 encoded text,
+// use ByteString.
+func Binary(key string, val []byte) Field {
+	return Field{Key: key, Type: zapcore.BinaryType, Interface: val}
+}
+
+// Bool constructs a field that carries a bool.
+func Bool(key string, val bool) Field {
+	var ival int64
+	if val {
+		ival = 1
+	}
+	return Field{Key: key, Type: zapcore.BoolType, Integer: ival}
+}
+
+// ByteString constructs a field that carries UTF-8 encoded text as a []byte.
+// To log opaque binary blobs (which aren't necessarily valid UTF-8), use
+// Binary.
+func ByteString(key string, val []byte) Field {
+	return Field{Key: key, Type: zapcore.ByteStringType, Interface: val}
+}
+
+// Complex128 constructs a field that carries a complex number. Unlike most
+// numeric fields, this costs an allocation (to convert the complex128 to
+// interface{}).
+func Complex128(key string, val complex128) Field {
+	return Field{Key: key, Type: zapcore.Complex128Type, Interface: val}
+}
+
+// Complex64 constructs a field that carries a complex number. Unlike most
+// numeric fields, this costs an allocation (to convert the complex64 to
+// interface{}).
+func Complex64(key string, val complex64) Field {
+	return Field{Key: key, Type: zapcore.Complex64Type, Interface: val}
+}
+
+// Float64 constructs a field that carries a float64. The way the
+// floating-point value is represented is encoder-dependent, so marshaling is
+// necessarily lazy.
+func Float64(key string, val float64) Field {
+	return Field{Key: key, Type: zapcore.Float64Type, Integer: int64(math.Float64bits(val))}
+}
+
+// Float32 constructs a field that carries a float32. The way the
+// floating-point value is represented is encoder-dependent, so marshaling is
+// necessarily lazy.
+func Float32(key string, val float32) Field {
+	return Field{Key: key, Type: zapcore.Float32Type, Integer: int64(math.Float32bits(val))}
+}
+
+// Int constructs a field with the given key and value.
+func Int(key string, val int) Field {
+	return Int64(key, int64(val))
+}
+
+// Int64 constructs a field with the given key and value.
+func Int64(key string, val int64) Field {
+	return Field{Key: key, Type: zapcore.Int64Type, Integer: val}
+}
+
+// Int32 constructs a field with the given key and value.
+func Int32(key string, val int32) Field {
+	return Field{Key: key, Type: zapcore.Int32Type, Integer: int64(val)}
+}
+
+// Int16 constructs a field with the given key and value.
+func Int16(key string, val int16) Field {
+	return Field{Key: key, Type: zapcore.Int16Type, Integer: int64(val)}
+}
+
+// Int8 constructs a field with the given key and value.
+func Int8(key string, val int8) Field {
+	return Field{Key: key, Type: zapcore.Int8Type, Integer: int64(val)}
+}
+
+// String constructs a field with the given key and value.
+func String(key string, val string) Field {
+	return Field{Key: key, Type: zapcore.StringType, String: val}
+}
+
+// Uint constructs a field with the given key and value.
+func Uint(key string, val uint) Field {
+	return Uint64(key, uint64(val))
+}
+
+// Uint64 constructs a field with the given key and value.
+func Uint64(key string, val uint64) Field {
+	return Field{Key: key, Type: zapcore.Uint64Type, Integer: int64(val)}
+}
+
+// Uint32 constructs a field with the given key and value.
+func Uint32(key string, val uint32) Field {
+	return Field{Key: key, Type: zapcore.Uint32Type, Integer: int64(val)}
+}
+
+// Uint16 constructs a field with the given key and value.
+func Uint16(key string, val uint16) Field {
+	return Field{Key: key, Type: zapcore.Uint16Type, Integer: int64(val)}
+}
+
+// Uint8 constructs a field with the given key and value.
+func Uint8(key string, val uint8) Field {
+	return Field{Key: key, Type: zapcore.Uint8Type, Integer: int64(val)}
+}
+
+// Uintptr constructs a field with the given key and value.
+func Uintptr(key string, val uintptr) Field {
+	return Field{Key: key, Type: zapcore.UintptrType, Integer: int64(val)}
+}
+
+// Reflect constructs a field with the given key and an arbitrary object. It uses
+// an encoding-appropriate, reflection-based function to lazily serialize nearly
+// any object into the logging context, but it's relatively slow and
+// allocation-heavy. Outside tests, Any is always a better choice.
+//
+// If encoding fails (e.g., trying to serialize a map[int]string to JSON), Reflect
+// includes the error message in the final log output.
+func Reflect(key string, val interface{}) Field {
+	return Field{Key: key, Type: zapcore.ReflectType, Interface: val}
+}
+
+// Namespace creates a named, isolated scope within the logger's context. All
+// subsequent fields will be added to the new namespace.
+//
+// This helps prevent key collisions when injecting loggers into sub-components
+// or third-party libraries.
+func Namespace(key string) Field {
+	return Field{Key: key, Type: zapcore.NamespaceType}
+}
+
+// Stringer constructs a field with the given key and the output of the value's
+// String method. The Stringer's String method is called lazily.
+func Stringer(key string, val fmt.Stringer) Field {
+	return Field{Key: key, Type: zapcore.StringerType, Interface: val}
+}
+
+// Time constructs a Field with the given key and value. The encoder
+// controls how the time is serialized.
+func Time(key string, val time.Time) Field {
+	return Field{Key: key, Type: zapcore.TimeType, Integer: val.UnixNano(), Interface: val.Location()}
+}
+
+// Stack constructs a field that stores a stacktrace of the current goroutine
+// under provided key. Keep in mind that taking a stacktrace is eager and
+// expensive (relatively speaking); this function both makes an allocation and
+// takes about two microseconds.
+func Stack(key string) Field {
+	// Returning the stacktrace as a string costs an allocation, but saves us
+	// from expanding the zapcore.Field union struct to include a byte slice. Since
+	// taking a stacktrace is already so expensive (~10us), the extra allocation
+	// is okay.
+	return String(key, takeStacktrace())
+}
+
+// Duration constructs a field with the given key and value. The encoder
+// controls how the duration is serialized.
+func Duration(key string, val time.Duration) Field {
+	return Field{Key: key, Type: zapcore.DurationType, Integer: int64(val)}
+}
+
+// Object constructs a field with the given key and ObjectMarshaler. It
+// provides a flexible, but still type-safe and efficient, way to add map- or
+// struct-like user-defined types to the logging context. The struct's
+// MarshalLogObject method is called lazily.
+func Object(key string, val zapcore.ObjectMarshaler) Field {
+	return Field{Key: key, Type: zapcore.ObjectMarshalerType, Interface: val}
+}
+
+// Any takes a key and an arbitrary value and chooses the best way to represent
+// them as a field, falling back to a reflection-based approach only if
+// necessary.
+//
+// Since byte/uint8 and rune/int32 are aliases, Any can't differentiate between
+// them. To minimize surprises, []byte values are treated as binary blobs, byte
+// values are treated as uint8, and runes are always treated as integers.
+func Any(key string, value interface{}) Field {
+	switch val := value.(type) {
+	case zapcore.ObjectMarshaler:
+		return Object(key, val)
+	case zapcore.ArrayMarshaler:
+		return Array(key, val)
+	case bool:
+		return Bool(key, val)
+	case []bool:
+		return Bools(key, val)
+	case complex128:
+		return Complex128(key, val)
+	case []complex128:
+		return Complex128s(key, val)
+	case complex64:
+		return Complex64(key, val)
+	case []complex64:
+		return Complex64s(key, val)
+	case float64:
+		return Float64(key, val)
+	case []float64:
+		return Float64s(key, val)
+	case float32:
+		return Float32(key, val)
+	case []float32:
+		return Float32s(key, val)
+	case int:
+		return Int(key, val)
+	case []int:
+		return Ints(key, val)
+	case int64:
+		return Int64(key, val)
+	case []int64:
+		return Int64s(key, val)
+	case int32:
+		return Int32(key, val)
+	case []int32:
+		return Int32s(key, val)
+	case int16:
+		return Int16(key, val)
+	case []int16:
+		return Int16s(key, val)
+	case int8:
+		return Int8(key, val)
+	case []int8:
+		return Int8s(key, val)
+	case string:
+		return String(key, val)
+	case []string:
+		return Strings(key, val)
+	case uint:
+		return Uint(key, val)
+	case []uint:
+		return Uints(key, val)
+	case uint64:
+		return Uint64(key, val)
+	case []uint64:
+		return Uint64s(key, val)
+	case uint32:
+		return Uint32(key, val)
+	case []uint32:
+		return Uint32s(key, val)
+	case uint16:
+		return Uint16(key, val)
+	case []uint16:
+		return Uint16s(key, val)
+	case uint8:
+		return Uint8(key, val)
+	case []byte:
+		return Binary(key, val)
+	case uintptr:
+		return Uintptr(key, val)
+	case []uintptr:
+		return Uintptrs(key, val)
+	case time.Time:
+		return Time(key, val)
+	case []time.Time:
+		return Times(key, val)
+	case time.Duration:
+		return Duration(key, val)
+	case []time.Duration:
+		return Durations(key, val)
+	case error:
+		return NamedError(key, val)
+	case []error:
+		return Errors(key, val)
+	case fmt.Stringer:
+		return Stringer(key, val)
+	default:
+		return Reflect(key, val)
+	}
+}
diff --git a/vendor/go.uber.org/zap/flag.go b/vendor/go.uber.org/zap/flag.go
new file mode 100644
index 0000000..1312875
--- /dev/null
+++ b/vendor/go.uber.org/zap/flag.go
@@ -0,0 +1,39 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zap
+
+import (
+	"flag"
+
+	"go.uber.org/zap/zapcore"
+)
+
+// LevelFlag uses the standard library's flag.Var to declare a global flag
+// with the specified name, default, and usage guidance. The returned value is
+// a pointer to the value of the flag.
+//
+// If you don't want to use the flag package's global state, you can use any
+// non-nil *Level as a flag.Value with your own *flag.FlagSet.
+func LevelFlag(name string, defaultLevel zapcore.Level, usage string) *zapcore.Level {
+	lvl := defaultLevel
+	flag.Var(&lvl, name, usage)
+	return &lvl
+}
diff --git a/vendor/go.uber.org/zap/glide.lock b/vendor/go.uber.org/zap/glide.lock
new file mode 100644
index 0000000..881b462
--- /dev/null
+++ b/vendor/go.uber.org/zap/glide.lock
@@ -0,0 +1,76 @@
+hash: f073ba522c06c88ea3075bde32a8aaf0969a840a66cab6318a0897d141ffee92
+updated: 2017-07-22T18:06:49.598185334-07:00
+imports:
+- name: go.uber.org/atomic
+  version: 4e336646b2ef9fc6e47be8e21594178f98e5ebcf
+- name: go.uber.org/multierr
+  version: 3c4937480c32f4c13a875a1829af76c98ca3d40a
+testImports:
+- name: github.com/apex/log
+  version: d9b960447bfa720077b2da653cc79e533455b499
+  subpackages:
+  - handlers/json
+- name: github.com/axw/gocov
+  version: 3a69a0d2a4ef1f263e2d92b041a69593d6964fe8
+  subpackages:
+  - gocov
+- name: github.com/davecgh/go-spew
+  version: 04cdfd42973bb9c8589fd6a731800cf222fde1a9
+  subpackages:
+  - spew
+- name: github.com/fatih/color
+  version: 62e9147c64a1ed519147b62a56a14e83e2be02c1
+- name: github.com/go-kit/kit
+  version: e10f5bf035be9af21fd5b2fb4469d5716c6ab07d
+  subpackages:
+  - log
+- name: github.com/go-logfmt/logfmt
+  version: 390ab7935ee28ec6b286364bba9b4dd6410cb3d5
+- name: github.com/go-stack/stack
+  version: 54be5f394ed2c3e19dac9134a40a95ba5a017f7b
+- name: github.com/golang/lint
+  version: c5fb716d6688a859aae56d26d3e6070808df29f7
+  subpackages:
+  - golint
+- name: github.com/kr/logfmt
+  version: b84e30acd515aadc4b783ad4ff83aff3299bdfe0
+- name: github.com/mattn/go-colorable
+  version: 3fa8c76f9daed4067e4a806fb7e4dc86455c6d6a
+- name: github.com/mattn/go-isatty
+  version: fc9e8d8ef48496124e79ae0df75490096eccf6fe
+- name: github.com/mattn/goveralls
+  version: 6efce81852ad1b7567c17ad71b03aeccc9dd9ae0
+- name: github.com/pborman/uuid
+  version: e790cca94e6cc75c7064b1332e63811d4aae1a53
+- name: github.com/pkg/errors
+  version: 645ef00459ed84a119197bfb8d8205042c6df63d
+- name: github.com/pmezard/go-difflib
+  version: d8ed2627bdf02c080bf22230dbb337003b7aba2d
+  subpackages:
+  - difflib
+- name: github.com/rs/zerolog
+  version: eed4c2b94d945e0b2456ad6aa518a443986b5f22
+- name: github.com/satori/go.uuid
+  version: 5bf94b69c6b68ee1b541973bb8e1144db23a194b
+- name: github.com/sirupsen/logrus
+  version: 7dd06bf38e1e13df288d471a57d5adbac106be9e
+- name: github.com/stretchr/testify
+  version: f6abca593680b2315d2075e0f5e2a9751e3f431a
+  subpackages:
+  - assert
+  - require
+- name: go.pedge.io/lion
+  version: 87958e8713f1fa138d993087133b97e976642159
+- name: golang.org/x/sys
+  version: c4489faa6e5ab84c0ef40d6ee878f7a030281f0f
+  subpackages:
+  - unix
+- name: golang.org/x/tools
+  version: 496819729719f9d07692195e0a94d6edd2251389
+  subpackages:
+  - cover
+- name: gopkg.in/inconshreveable/log15.v2
+  version: b105bd37f74e5d9dc7b6ad7806715c7a2b83fd3f
+  subpackages:
+  - stack
+  - term
diff --git a/vendor/go.uber.org/zap/glide.yaml b/vendor/go.uber.org/zap/glide.yaml
new file mode 100644
index 0000000..9441259
--- /dev/null
+++ b/vendor/go.uber.org/zap/glide.yaml
@@ -0,0 +1,35 @@
+package: go.uber.org/zap
+license: MIT
+import:
+- package: go.uber.org/atomic
+  version: ^1
+- package: go.uber.org/multierr
+  version: ^1
+testImport:
+- package: github.com/satori/go.uuid
+- package: github.com/sirupsen/logrus
+- package: github.com/apex/log
+  subpackages:
+  - handlers/json
+- package: github.com/go-kit/kit
+  subpackages:
+  - log
+- package: github.com/stretchr/testify
+  subpackages:
+  - assert
+  - require
+- package: gopkg.in/inconshreveable/log15.v2
+- package: github.com/mattn/goveralls
+- package: github.com/pborman/uuid
+- package: github.com/pkg/errors
+- package: go.pedge.io/lion
+- package: github.com/rs/zerolog
+- package: golang.org/x/tools
+  subpackages:
+  - cover
+- package: github.com/golang/lint
+  subpackages:
+  - golint
+- package: github.com/axw/gocov
+  subpackages:
+  - gocov
diff --git a/vendor/go.uber.org/zap/global.go b/vendor/go.uber.org/zap/global.go
new file mode 100644
index 0000000..d02232e
--- /dev/null
+++ b/vendor/go.uber.org/zap/global.go
@@ -0,0 +1,169 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zap
+
+import (
+	"bytes"
+	"fmt"
+	"log"
+	"os"
+	"sync"
+
+	"go.uber.org/zap/zapcore"
+)
+
+const (
+	_stdLogDefaultDepth      = 2
+	_loggerWriterDepth       = 2
+	_programmerErrorTemplate = "You've found a bug in zap! Please file a bug at " +
+		"https://github.com/uber-go/zap/issues/new and reference this error: %v"
+)
+
+var (
+	_globalMu sync.RWMutex
+	_globalL  = NewNop()
+	_globalS  = _globalL.Sugar()
+)
+
+// L returns the global Logger, which can be reconfigured with ReplaceGlobals.
+// It's safe for concurrent use.
+func L() *Logger {
+	_globalMu.RLock()
+	l := _globalL
+	_globalMu.RUnlock()
+	return l
+}
+
+// S returns the global SugaredLogger, which can be reconfigured with
+// ReplaceGlobals. It's safe for concurrent use.
+func S() *SugaredLogger {
+	_globalMu.RLock()
+	s := _globalS
+	_globalMu.RUnlock()
+	return s
+}
+
+// ReplaceGlobals replaces the global Logger and SugaredLogger, and returns a
+// function to restore the original values. It's safe for concurrent use.
+func ReplaceGlobals(logger *Logger) func() {
+	_globalMu.Lock()
+	prev := _globalL
+	_globalL = logger
+	_globalS = logger.Sugar()
+	_globalMu.Unlock()
+	return func() { ReplaceGlobals(prev) }
+}
+
+// NewStdLog returns a *log.Logger which writes to the supplied zap Logger at
+// InfoLevel. To redirect the standard library's package-global logging
+// functions, use RedirectStdLog instead.
+func NewStdLog(l *Logger) *log.Logger {
+	logger := l.WithOptions(AddCallerSkip(_stdLogDefaultDepth + _loggerWriterDepth))
+	f := logger.Info
+	return log.New(&loggerWriter{f}, "" /* prefix */, 0 /* flags */)
+}
+
+// NewStdLogAt returns *log.Logger which writes to supplied zap logger at
+// required level.
+func NewStdLogAt(l *Logger, level zapcore.Level) (*log.Logger, error) {
+	logger := l.WithOptions(AddCallerSkip(_stdLogDefaultDepth + _loggerWriterDepth))
+	logFunc, err := levelToFunc(logger, level)
+	if err != nil {
+		return nil, err
+	}
+	return log.New(&loggerWriter{logFunc}, "" /* prefix */, 0 /* flags */), nil
+}
+
+// RedirectStdLog redirects output from the standard library's package-global
+// logger to the supplied logger at InfoLevel. Since zap already handles caller
+// annotations, timestamps, etc., it automatically disables the standard
+// library's annotations and prefixing.
+//
+// It returns a function to restore the original prefix and flags and reset the
+// standard library's output to os.Stderr.
+func RedirectStdLog(l *Logger) func() {
+	f, err := redirectStdLogAt(l, InfoLevel)
+	if err != nil {
+		// Can't get here, since passing InfoLevel to redirectStdLogAt always
+		// works.
+		panic(fmt.Sprintf(_programmerErrorTemplate, err))
+	}
+	return f
+}
+
+// RedirectStdLogAt redirects output from the standard library's package-global
+// logger to the supplied logger at the specified level. Since zap already
+// handles caller annotations, timestamps, etc., it automatically disables the
+// standard library's annotations and prefixing.
+//
+// It returns a function to restore the original prefix and flags and reset the
+// standard library's output to os.Stderr.
+func RedirectStdLogAt(l *Logger, level zapcore.Level) (func(), error) {
+	return redirectStdLogAt(l, level)
+}
+
+func redirectStdLogAt(l *Logger, level zapcore.Level) (func(), error) {
+	flags := log.Flags()
+	prefix := log.Prefix()
+	log.SetFlags(0)
+	log.SetPrefix("")
+	logger := l.WithOptions(AddCallerSkip(_stdLogDefaultDepth + _loggerWriterDepth))
+	logFunc, err := levelToFunc(logger, level)
+	if err != nil {
+		return nil, err
+	}
+	log.SetOutput(&loggerWriter{logFunc})
+	return func() {
+		log.SetFlags(flags)
+		log.SetPrefix(prefix)
+		log.SetOutput(os.Stderr)
+	}, nil
+}
+
+func levelToFunc(logger *Logger, lvl zapcore.Level) (func(string, ...Field), error) {
+	switch lvl {
+	case DebugLevel:
+		return logger.Debug, nil
+	case InfoLevel:
+		return logger.Info, nil
+	case WarnLevel:
+		return logger.Warn, nil
+	case ErrorLevel:
+		return logger.Error, nil
+	case DPanicLevel:
+		return logger.DPanic, nil
+	case PanicLevel:
+		return logger.Panic, nil
+	case FatalLevel:
+		return logger.Fatal, nil
+	}
+	return nil, fmt.Errorf("unrecognized level: %q", lvl)
+}
+
+type loggerWriter struct {
+	logFunc func(msg string, fields ...Field)
+}
+
+func (l *loggerWriter) Write(p []byte) (int, error) {
+	p = bytes.TrimSpace(p)
+	l.logFunc(string(p))
+	return len(p), nil
+}
diff --git a/vendor/go.uber.org/zap/http_handler.go b/vendor/go.uber.org/zap/http_handler.go
new file mode 100644
index 0000000..1b0ecac
--- /dev/null
+++ b/vendor/go.uber.org/zap/http_handler.go
@@ -0,0 +1,81 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zap
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+
+	"go.uber.org/zap/zapcore"
+)
+
+// ServeHTTP is a simple JSON endpoint that can report on or change the current
+// logging level.
+//
+// GET requests return a JSON description of the current logging level. PUT
+// requests change the logging level and expect a payload like:
+//   {"level":"info"}
+//
+// It's perfectly safe to change the logging level while a program is running.
+func (lvl AtomicLevel) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	type errorResponse struct {
+		Error string `json:"error"`
+	}
+	type payload struct {
+		Level *zapcore.Level `json:"level"`
+	}
+
+	enc := json.NewEncoder(w)
+
+	switch r.Method {
+
+	case http.MethodGet:
+		current := lvl.Level()
+		enc.Encode(payload{Level: &current})
+
+	case http.MethodPut:
+		var req payload
+
+		if errmess := func() string {
+			if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+				return fmt.Sprintf("Request body must be well-formed JSON: %v", err)
+			}
+			if req.Level == nil {
+				return "Must specify a logging level."
+			}
+			return ""
+		}(); errmess != "" {
+			w.WriteHeader(http.StatusBadRequest)
+			enc.Encode(errorResponse{Error: errmess})
+			return
+		}
+
+		lvl.SetLevel(*req.Level)
+		enc.Encode(req)
+
+	default:
+		w.WriteHeader(http.StatusMethodNotAllowed)
+		enc.Encode(errorResponse{
+			Error: "Only GET and PUT are supported.",
+		})
+	}
+}
diff --git a/vendor/go.uber.org/zap/internal/bufferpool/bufferpool.go b/vendor/go.uber.org/zap/internal/bufferpool/bufferpool.go
new file mode 100644
index 0000000..dad583a
--- /dev/null
+++ b/vendor/go.uber.org/zap/internal/bufferpool/bufferpool.go
@@ -0,0 +1,31 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+// Package bufferpool houses zap's shared internal buffer pool. Third-party
+// packages can recreate the same functionality with buffers.NewPool.
+package bufferpool
+
+import "go.uber.org/zap/buffer"
+
+var (
+	_pool = buffer.NewPool()
+	// Get retrieves a buffer from the pool, creating one if necessary.
+	Get = _pool.Get
+)
diff --git a/vendor/go.uber.org/zap/internal/color/color.go b/vendor/go.uber.org/zap/internal/color/color.go
new file mode 100644
index 0000000..c4d5d02
--- /dev/null
+++ b/vendor/go.uber.org/zap/internal/color/color.go
@@ -0,0 +1,44 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+// Package color adds coloring functionality for TTY output.
+package color
+
+import "fmt"
+
+// Foreground colors.
+const (
+	Black Color = iota + 30
+	Red
+	Green
+	Yellow
+	Blue
+	Magenta
+	Cyan
+	White
+)
+
+// Color represents a text color.
+type Color uint8
+
+// Add adds the coloring to the given string.
+func (c Color) Add(s string) string {
+	return fmt.Sprintf("\x1b[%dm%s\x1b[0m", uint8(c), s)
+}
diff --git a/vendor/go.uber.org/zap/internal/exit/exit.go b/vendor/go.uber.org/zap/internal/exit/exit.go
new file mode 100644
index 0000000..dfc5b05
--- /dev/null
+++ b/vendor/go.uber.org/zap/internal/exit/exit.go
@@ -0,0 +1,64 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+// Package exit provides stubs so that unit tests can exercise code that calls
+// os.Exit(1).
+package exit
+
+import "os"
+
+var real = func() { os.Exit(1) }
+
+// Exit normally terminates the process by calling os.Exit(1). If the package
+// is stubbed, it instead records a call in the testing spy.
+func Exit() {
+	real()
+}
+
+// A StubbedExit is a testing fake for os.Exit.
+type StubbedExit struct {
+	Exited bool
+	prev   func()
+}
+
+// Stub substitutes a fake for the call to os.Exit(1).
+func Stub() *StubbedExit {
+	s := &StubbedExit{prev: real}
+	real = s.exit
+	return s
+}
+
+// WithStub runs the supplied function with Exit stubbed. It returns the stub
+// used, so that users can test whether the process would have crashed.
+func WithStub(f func()) *StubbedExit {
+	s := Stub()
+	defer s.Unstub()
+	f()
+	return s
+}
+
+// Unstub restores the previous exit function.
+func (se *StubbedExit) Unstub() {
+	real = se.prev
+}
+
+func (se *StubbedExit) exit() {
+	se.Exited = true
+}
diff --git a/vendor/go.uber.org/zap/level.go b/vendor/go.uber.org/zap/level.go
new file mode 100644
index 0000000..3567a9a
--- /dev/null
+++ b/vendor/go.uber.org/zap/level.go
@@ -0,0 +1,132 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zap
+
+import (
+	"go.uber.org/atomic"
+	"go.uber.org/zap/zapcore"
+)
+
+const (
+	// DebugLevel logs are typically voluminous, and are usually disabled in
+	// production.
+	DebugLevel = zapcore.DebugLevel
+	// InfoLevel is the default logging priority.
+	InfoLevel = zapcore.InfoLevel
+	// WarnLevel logs are more important than Info, but don't need individual
+	// human review.
+	WarnLevel = zapcore.WarnLevel
+	// ErrorLevel logs are high-priority. If an application is running smoothly,
+	// it shouldn't generate any error-level logs.
+	ErrorLevel = zapcore.ErrorLevel
+	// DPanicLevel logs are particularly important errors. In development the
+	// logger panics after writing the message.
+	DPanicLevel = zapcore.DPanicLevel
+	// PanicLevel logs a message, then panics.
+	PanicLevel = zapcore.PanicLevel
+	// FatalLevel logs a message, then calls os.Exit(1).
+	FatalLevel = zapcore.FatalLevel
+)
+
+// LevelEnablerFunc is a convenient way to implement zapcore.LevelEnabler with
+// an anonymous function.
+//
+// It's particularly useful when splitting log output between different
+// outputs (e.g., standard error and standard out). For sample code, see the
+// package-level AdvancedConfiguration example.
+type LevelEnablerFunc func(zapcore.Level) bool
+
+// Enabled calls the wrapped function.
+func (f LevelEnablerFunc) Enabled(lvl zapcore.Level) bool { return f(lvl) }
+
+// An AtomicLevel is an atomically changeable, dynamic logging level. It lets
+// you safely change the log level of a tree of loggers (the root logger and
+// any children created by adding context) at runtime.
+//
+// The AtomicLevel itself is an http.Handler that serves a JSON endpoint to
+// alter its level.
+//
+// AtomicLevels must be created with the NewAtomicLevel constructor to allocate
+// their internal atomic pointer.
+type AtomicLevel struct {
+	l *atomic.Int32
+}
+
+// NewAtomicLevel creates an AtomicLevel with InfoLevel and above logging
+// enabled.
+func NewAtomicLevel() AtomicLevel {
+	return AtomicLevel{
+		l: atomic.NewInt32(int32(InfoLevel)),
+	}
+}
+
+// NewAtomicLevelAt is a convenience function that creates an AtomicLevel
+// and then calls SetLevel with the given level.
+func NewAtomicLevelAt(l zapcore.Level) AtomicLevel {
+	a := NewAtomicLevel()
+	a.SetLevel(l)
+	return a
+}
+
+// Enabled implements the zapcore.LevelEnabler interface, which allows the
+// AtomicLevel to be used in place of traditional static levels.
+func (lvl AtomicLevel) Enabled(l zapcore.Level) bool {
+	return lvl.Level().Enabled(l)
+}
+
+// Level returns the minimum enabled log level.
+func (lvl AtomicLevel) Level() zapcore.Level {
+	return zapcore.Level(int8(lvl.l.Load()))
+}
+
+// SetLevel alters the logging level.
+func (lvl AtomicLevel) SetLevel(l zapcore.Level) {
+	lvl.l.Store(int32(l))
+}
+
+// String returns the string representation of the underlying Level.
+func (lvl AtomicLevel) String() string {
+	return lvl.Level().String()
+}
+
+// UnmarshalText unmarshals the text to an AtomicLevel. It uses the same text
+// representations as the static zapcore.Levels ("debug", "info", "warn",
+// "error", "dpanic", "panic", and "fatal").
+func (lvl *AtomicLevel) UnmarshalText(text []byte) error {
+	if lvl.l == nil {
+		lvl.l = &atomic.Int32{}
+	}
+
+	var l zapcore.Level
+	if err := l.UnmarshalText(text); err != nil {
+		return err
+	}
+
+	lvl.SetLevel(l)
+	return nil
+}
+
+// MarshalText marshals the AtomicLevel to a byte slice. It uses the same
+// text representation as the static zapcore.Levels ("debug", "info", "warn",
+// "error", "dpanic", "panic", and "fatal").
+func (lvl AtomicLevel) MarshalText() (text []byte, err error) {
+	return lvl.Level().MarshalText()
+}
diff --git a/vendor/go.uber.org/zap/logger.go b/vendor/go.uber.org/zap/logger.go
new file mode 100644
index 0000000..dc8f6e3
--- /dev/null
+++ b/vendor/go.uber.org/zap/logger.go
@@ -0,0 +1,305 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zap
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"runtime"
+	"strings"
+	"time"
+
+	"go.uber.org/zap/zapcore"
+)
+
+// A Logger provides fast, leveled, structured logging. All methods are safe
+// for concurrent use.
+//
+// The Logger is designed for contexts in which every microsecond and every
+// allocation matters, so its API intentionally favors performance and type
+// safety over brevity. For most applications, the SugaredLogger strikes a
+// better balance between performance and ergonomics.
+type Logger struct {
+	core zapcore.Core
+
+	development bool
+	name        string
+	errorOutput zapcore.WriteSyncer
+
+	addCaller bool
+	addStack  zapcore.LevelEnabler
+
+	callerSkip int
+}
+
+// New constructs a new Logger from the provided zapcore.Core and Options. If
+// the passed zapcore.Core is nil, it falls back to using a no-op
+// implementation.
+//
+// This is the most flexible way to construct a Logger, but also the most
+// verbose. For typical use cases, the highly-opinionated presets
+// (NewProduction, NewDevelopment, and NewExample) or the Config struct are
+// more convenient.
+//
+// For sample code, see the package-level AdvancedConfiguration example.
+func New(core zapcore.Core, options ...Option) *Logger {
+	if core == nil {
+		return NewNop()
+	}
+	log := &Logger{
+		core:        core,
+		errorOutput: zapcore.Lock(os.Stderr),
+		addStack:    zapcore.FatalLevel + 1,
+	}
+	return log.WithOptions(options...)
+}
+
+// NewNop returns a no-op Logger. It never writes out logs or internal errors,
+// and it never runs user-defined hooks.
+//
+// Using WithOptions to replace the Core or error output of a no-op Logger can
+// re-enable logging.
+func NewNop() *Logger {
+	return &Logger{
+		core:        zapcore.NewNopCore(),
+		errorOutput: zapcore.AddSync(ioutil.Discard),
+		addStack:    zapcore.FatalLevel + 1,
+	}
+}
+
+// NewProduction builds a sensible production Logger that writes InfoLevel and
+// above logs to standard error as JSON.
+//
+// It's a shortcut for NewProductionConfig().Build(...Option).
+func NewProduction(options ...Option) (*Logger, error) {
+	return NewProductionConfig().Build(options...)
+}
+
+// NewDevelopment builds a development Logger that writes DebugLevel and above
+// logs to standard error in a human-friendly format.
+//
+// It's a shortcut for NewDevelopmentConfig().Build(...Option).
+func NewDevelopment(options ...Option) (*Logger, error) {
+	return NewDevelopmentConfig().Build(options...)
+}
+
+// NewExample builds a Logger that's designed for use in zap's testable
+// examples. It writes DebugLevel and above logs to standard out as JSON, but
+// omits the timestamp and calling function to keep example output
+// short and deterministic.
+func NewExample(options ...Option) *Logger {
+	encoderCfg := zapcore.EncoderConfig{
+		MessageKey:     "msg",
+		LevelKey:       "level",
+		NameKey:        "logger",
+		EncodeLevel:    zapcore.LowercaseLevelEncoder,
+		EncodeTime:     zapcore.ISO8601TimeEncoder,
+		EncodeDuration: zapcore.StringDurationEncoder,
+	}
+	core := zapcore.NewCore(zapcore.NewJSONEncoder(encoderCfg), os.Stdout, DebugLevel)
+	return New(core).WithOptions(options...)
+}
+
+// Sugar wraps the Logger to provide a more ergonomic, but slightly slower,
+// API. Sugaring a Logger is quite inexpensive, so it's reasonable for a
+// single application to use both Loggers and SugaredLoggers, converting
+// between them on the boundaries of performance-sensitive code.
+func (log *Logger) Sugar() *SugaredLogger {
+	core := log.clone()
+	core.callerSkip += 2
+	return &SugaredLogger{core}
+}
+
+// Named adds a new path segment to the logger's name. Segments are joined by
+// periods. By default, Loggers are unnamed.
+func (log *Logger) Named(s string) *Logger {
+	if s == "" {
+		return log
+	}
+	l := log.clone()
+	if log.name == "" {
+		l.name = s
+	} else {
+		l.name = strings.Join([]string{l.name, s}, ".")
+	}
+	return l
+}
+
+// WithOptions clones the current Logger, applies the supplied Options, and
+// returns the resulting Logger. It's safe to use concurrently.
+func (log *Logger) WithOptions(opts ...Option) *Logger {
+	c := log.clone()
+	for _, opt := range opts {
+		opt.apply(c)
+	}
+	return c
+}
+
+// With creates a child logger and adds structured context to it. Fields added
+// to the child don't affect the parent, and vice versa.
+func (log *Logger) With(fields ...Field) *Logger {
+	if len(fields) == 0 {
+		return log
+	}
+	l := log.clone()
+	l.core = l.core.With(fields)
+	return l
+}
+
+// Check returns a CheckedEntry if logging a message at the specified level
+// is enabled. It's a completely optional optimization; in high-performance
+// applications, Check can help avoid allocating a slice to hold fields.
+func (log *Logger) Check(lvl zapcore.Level, msg string) *zapcore.CheckedEntry {
+	return log.check(lvl, msg)
+}
+
+// Debug logs a message at DebugLevel. The message includes any fields passed
+// at the log site, as well as any fields accumulated on the logger.
+func (log *Logger) Debug(msg string, fields ...Field) {
+	if ce := log.check(DebugLevel, msg); ce != nil {
+		ce.Write(fields...)
+	}
+}
+
+// Info logs a message at InfoLevel. The message includes any fields passed
+// at the log site, as well as any fields accumulated on the logger.
+func (log *Logger) Info(msg string, fields ...Field) {
+	if ce := log.check(InfoLevel, msg); ce != nil {
+		ce.Write(fields...)
+	}
+}
+
+// Warn logs a message at WarnLevel. The message includes any fields passed
+// at the log site, as well as any fields accumulated on the logger.
+func (log *Logger) Warn(msg string, fields ...Field) {
+	if ce := log.check(WarnLevel, msg); ce != nil {
+		ce.Write(fields...)
+	}
+}
+
+// Error logs a message at ErrorLevel. The message includes any fields passed
+// at the log site, as well as any fields accumulated on the logger.
+func (log *Logger) Error(msg string, fields ...Field) {
+	if ce := log.check(ErrorLevel, msg); ce != nil {
+		ce.Write(fields...)
+	}
+}
+
+// DPanic logs a message at DPanicLevel. The message includes any fields
+// passed at the log site, as well as any fields accumulated on the logger.
+//
+// If the logger is in development mode, it then panics (DPanic means
+// "development panic"). This is useful for catching errors that are
+// recoverable, but shouldn't ever happen.
+func (log *Logger) DPanic(msg string, fields ...Field) {
+	if ce := log.check(DPanicLevel, msg); ce != nil {
+		ce.Write(fields...)
+	}
+}
+
+// Panic logs a message at PanicLevel. The message includes any fields passed
+// at the log site, as well as any fields accumulated on the logger.
+//
+// The logger then panics, even if logging at PanicLevel is disabled.
+func (log *Logger) Panic(msg string, fields ...Field) {
+	if ce := log.check(PanicLevel, msg); ce != nil {
+		ce.Write(fields...)
+	}
+}
+
+// Fatal logs a message at FatalLevel. The message includes any fields passed
+// at the log site, as well as any fields accumulated on the logger.
+//
+// The logger then calls os.Exit(1), even if logging at FatalLevel is
+// disabled.
+func (log *Logger) Fatal(msg string, fields ...Field) {
+	if ce := log.check(FatalLevel, msg); ce != nil {
+		ce.Write(fields...)
+	}
+}
+
+// Sync calls the underlying Core's Sync method, flushing any buffered log
+// entries. Applications should take care to call Sync before exiting.
+func (log *Logger) Sync() error {
+	return log.core.Sync()
+}
+
+// Core returns the Logger's underlying zapcore.Core.
+func (log *Logger) Core() zapcore.Core {
+	return log.core
+}
+
+func (log *Logger) clone() *Logger {
+	copy := *log
+	return &copy
+}
+
+func (log *Logger) check(lvl zapcore.Level, msg string) *zapcore.CheckedEntry {
+	// check must always be called directly by a method in the Logger interface
+	// (e.g., Check, Info, Fatal).
+	const callerSkipOffset = 2
+
+	// Create basic checked entry thru the core; this will be non-nil if the
+	// log message will actually be written somewhere.
+	ent := zapcore.Entry{
+		LoggerName: log.name,
+		Time:       time.Now(),
+		Level:      lvl,
+		Message:    msg,
+	}
+	ce := log.core.Check(ent, nil)
+	willWrite := ce != nil
+
+	// Set up any required terminal behavior.
+	switch ent.Level {
+	case zapcore.PanicLevel:
+		ce = ce.Should(ent, zapcore.WriteThenPanic)
+	case zapcore.FatalLevel:
+		ce = ce.Should(ent, zapcore.WriteThenFatal)
+	case zapcore.DPanicLevel:
+		if log.development {
+			ce = ce.Should(ent, zapcore.WriteThenPanic)
+		}
+	}
+
+	// Only do further annotation if we're going to write this message; checked
+	// entries that exist only for terminal behavior don't benefit from
+	// annotation.
+	if !willWrite {
+		return ce
+	}
+
+	// Thread the error output through to the CheckedEntry.
+	ce.ErrorOutput = log.errorOutput
+	if log.addCaller {
+		ce.Entry.Caller = zapcore.NewEntryCaller(runtime.Caller(log.callerSkip + callerSkipOffset))
+		if !ce.Entry.Caller.Defined {
+			fmt.Fprintf(log.errorOutput, "%v Logger.check error: failed to get caller\n", time.Now().UTC())
+			log.errorOutput.Sync()
+		}
+	}
+	if log.addStack.Enabled(ce.Entry.Level) {
+		ce.Entry.Stack = Stack("").String
+	}
+
+	return ce
+}
diff --git a/vendor/go.uber.org/zap/options.go b/vendor/go.uber.org/zap/options.go
new file mode 100644
index 0000000..7a6b0fc
--- /dev/null
+++ b/vendor/go.uber.org/zap/options.go
@@ -0,0 +1,109 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zap
+
+import "go.uber.org/zap/zapcore"
+
+// An Option configures a Logger.
+type Option interface {
+	apply(*Logger)
+}
+
+// optionFunc wraps a func so it satisfies the Option interface.
+type optionFunc func(*Logger)
+
+func (f optionFunc) apply(log *Logger) {
+	f(log)
+}
+
+// WrapCore wraps or replaces the Logger's underlying zapcore.Core.
+func WrapCore(f func(zapcore.Core) zapcore.Core) Option {
+	return optionFunc(func(log *Logger) {
+		log.core = f(log.core)
+	})
+}
+
+// Hooks registers functions which will be called each time the Logger writes
+// out an Entry. Repeated use of Hooks is additive.
+//
+// Hooks are useful for simple side effects, like capturing metrics for the
+// number of emitted logs. More complex side effects, including anything that
+// requires access to the Entry's structured fields, should be implemented as
+// a zapcore.Core instead. See zapcore.RegisterHooks for details.
+func Hooks(hooks ...func(zapcore.Entry) error) Option {
+	return optionFunc(func(log *Logger) {
+		log.core = zapcore.RegisterHooks(log.core, hooks...)
+	})
+}
+
+// Fields adds fields to the Logger.
+func Fields(fs ...Field) Option {
+	return optionFunc(func(log *Logger) {
+		log.core = log.core.With(fs)
+	})
+}
+
+// ErrorOutput sets the destination for errors generated by the Logger. Note
+// that this option only affects internal errors; for sample code that sends
+// error-level logs to a different location from info- and debug-level logs,
+// see the package-level AdvancedConfiguration example.
+//
+// The supplied WriteSyncer must be safe for concurrent use. The Open and
+// zapcore.Lock functions are the simplest ways to protect files with a mutex.
+func ErrorOutput(w zapcore.WriteSyncer) Option {
+	return optionFunc(func(log *Logger) {
+		log.errorOutput = w
+	})
+}
+
+// Development puts the logger in development mode, which makes DPanic-level
+// logs panic instead of simply logging an error.
+func Development() Option {
+	return optionFunc(func(log *Logger) {
+		log.development = true
+	})
+}
+
+// AddCaller configures the Logger to annotate each message with the filename
+// and line number of zap's caller.
+func AddCaller() Option {
+	return optionFunc(func(log *Logger) {
+		log.addCaller = true
+	})
+}
+
+// AddCallerSkip increases the number of callers skipped by caller annotation
+// (as enabled by the AddCaller option). When building wrappers around the
+// Logger and SugaredLogger, supplying this Option prevents zap from always
+// reporting the wrapper code as the caller.
+func AddCallerSkip(skip int) Option {
+	return optionFunc(func(log *Logger) {
+		log.callerSkip += skip
+	})
+}
+
+// AddStacktrace configures the Logger to record a stack trace for all messages at
+// or above a given level.
+func AddStacktrace(lvl zapcore.LevelEnabler) Option {
+	return optionFunc(func(log *Logger) {
+		log.addStack = lvl
+	})
+}
diff --git a/vendor/go.uber.org/zap/sink.go b/vendor/go.uber.org/zap/sink.go
new file mode 100644
index 0000000..ff0becf
--- /dev/null
+++ b/vendor/go.uber.org/zap/sink.go
@@ -0,0 +1,161 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zap
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"net/url"
+	"os"
+	"strings"
+	"sync"
+
+	"go.uber.org/zap/zapcore"
+)
+
+const schemeFile = "file"
+
+var (
+	_sinkMutex     sync.RWMutex
+	_sinkFactories map[string]func(*url.URL) (Sink, error) // keyed by scheme
+)
+
+func init() {
+	resetSinkRegistry()
+}
+
+func resetSinkRegistry() {
+	_sinkMutex.Lock()
+	defer _sinkMutex.Unlock()
+
+	_sinkFactories = map[string]func(*url.URL) (Sink, error){
+		schemeFile: newFileSink,
+	}
+}
+
+// Sink defines the interface to write to and close logger destinations.
+type Sink interface {
+	zapcore.WriteSyncer
+	io.Closer
+}
+
+type nopCloserSink struct{ zapcore.WriteSyncer }
+
+func (nopCloserSink) Close() error { return nil }
+
+type errSinkNotFound struct {
+	scheme string
+}
+
+func (e *errSinkNotFound) Error() string {
+	return fmt.Sprintf("no sink found for scheme %q", e.scheme)
+}
+
+// RegisterSink registers a user-supplied factory for all sinks with a
+// particular scheme.
+//
+// All schemes must be ASCII, valid under section 3.1 of RFC 3986
+// (https://tools.ietf.org/html/rfc3986#section-3.1), and must not already
+// have a factory registered. Zap automatically registers a factory for the
+// "file" scheme.
+func RegisterSink(scheme string, factory func(*url.URL) (Sink, error)) error {
+	_sinkMutex.Lock()
+	defer _sinkMutex.Unlock()
+
+	if scheme == "" {
+		return errors.New("can't register a sink factory for empty string")
+	}
+	normalized, err := normalizeScheme(scheme)
+	if err != nil {
+		return fmt.Errorf("%q is not a valid scheme: %v", scheme, err)
+	}
+	if _, ok := _sinkFactories[normalized]; ok {
+		return fmt.Errorf("sink factory already registered for scheme %q", normalized)
+	}
+	_sinkFactories[normalized] = factory
+	return nil
+}
+
+func newSink(rawURL string) (Sink, error) {
+	u, err := url.Parse(rawURL)
+	if err != nil {
+		return nil, fmt.Errorf("can't parse %q as a URL: %v", rawURL, err)
+	}
+	if u.Scheme == "" {
+		u.Scheme = schemeFile
+	}
+
+	_sinkMutex.RLock()
+	factory, ok := _sinkFactories[u.Scheme]
+	_sinkMutex.RUnlock()
+	if !ok {
+		return nil, &errSinkNotFound{u.Scheme}
+	}
+	return factory(u)
+}
+
+func newFileSink(u *url.URL) (Sink, error) {
+	if u.User != nil {
+		return nil, fmt.Errorf("user and password not allowed with file URLs: got %v", u)
+	}
+	if u.Fragment != "" {
+		return nil, fmt.Errorf("fragments not allowed with file URLs: got %v", u)
+	}
+	if u.RawQuery != "" {
+		return nil, fmt.Errorf("query parameters not allowed with file URLs: got %v", u)
+	}
+	// Error messages are better if we check hostname and port separately.
+	if u.Port() != "" {
+		return nil, fmt.Errorf("ports not allowed with file URLs: got %v", u)
+	}
+	if hn := u.Hostname(); hn != "" && hn != "localhost" {
+		return nil, fmt.Errorf("file URLs must leave host empty or use localhost: got %v", u)
+	}
+	switch u.Path {
+	case "stdout":
+		return nopCloserSink{os.Stdout}, nil
+	case "stderr":
+		return nopCloserSink{os.Stderr}, nil
+	}
+	return os.OpenFile(u.Path, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0644)
+}
+
+func normalizeScheme(s string) (string, error) {
+	// https://tools.ietf.org/html/rfc3986#section-3.1
+	s = strings.ToLower(s)
+	if first := s[0]; 'a' > first || 'z' < first {
+		return "", errors.New("must start with a letter")
+	}
+	for i := 1; i < len(s); i++ { // iterate over bytes, not runes
+		c := s[i]
+		switch {
+		case 'a' <= c && c <= 'z':
+			continue
+		case '0' <= c && c <= '9':
+			continue
+		case c == '.' || c == '+' || c == '-':
+			continue
+		}
+		return "", fmt.Errorf("may not contain %q", c)
+	}
+	return s, nil
+}
diff --git a/vendor/go.uber.org/zap/stacktrace.go b/vendor/go.uber.org/zap/stacktrace.go
new file mode 100644
index 0000000..100fac2
--- /dev/null
+++ b/vendor/go.uber.org/zap/stacktrace.go
@@ -0,0 +1,126 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zap
+
+import (
+	"runtime"
+	"strings"
+	"sync"
+
+	"go.uber.org/zap/internal/bufferpool"
+)
+
+const _zapPackage = "go.uber.org/zap"
+
+var (
+	_stacktracePool = sync.Pool{
+		New: func() interface{} {
+			return newProgramCounters(64)
+		},
+	}
+
+	// We add "." and "/" suffixes to the package name to ensure we only match
+	// the exact package and not any package with the same prefix.
+	_zapStacktracePrefixes       = addPrefix(_zapPackage, ".", "/")
+	_zapStacktraceVendorContains = addPrefix("/vendor/", _zapStacktracePrefixes...)
+)
+
+func takeStacktrace() string {
+	buffer := bufferpool.Get()
+	defer buffer.Free()
+	programCounters := _stacktracePool.Get().(*programCounters)
+	defer _stacktracePool.Put(programCounters)
+
+	var numFrames int
+	for {
+		// Skip the call to runtime.Counters and takeStacktrace so that the
+		// program counters start at the caller of takeStacktrace.
+		numFrames = runtime.Callers(2, programCounters.pcs)
+		if numFrames < len(programCounters.pcs) {
+			break
+		}
+		// Don't put the too-short counter slice back into the pool; this lets
+		// the pool adjust if we consistently take deep stacktraces.
+		programCounters = newProgramCounters(len(programCounters.pcs) * 2)
+	}
+
+	i := 0
+	skipZapFrames := true // skip all consecutive zap frames at the beginning.
+	frames := runtime.CallersFrames(programCounters.pcs[:numFrames])
+
+	// Note: On the last iteration, frames.Next() returns false, with a valid
+	// frame, but we ignore this frame. The last frame is a a runtime frame which
+	// adds noise, since it's only either runtime.main or runtime.goexit.
+	for frame, more := frames.Next(); more; frame, more = frames.Next() {
+		if skipZapFrames && isZapFrame(frame.Function) {
+			continue
+		} else {
+			skipZapFrames = false
+		}
+
+		if i != 0 {
+			buffer.AppendByte('\n')
+		}
+		i++
+		buffer.AppendString(frame.Function)
+		buffer.AppendByte('\n')
+		buffer.AppendByte('\t')
+		buffer.AppendString(frame.File)
+		buffer.AppendByte(':')
+		buffer.AppendInt(int64(frame.Line))
+	}
+
+	return buffer.String()
+}
+
+func isZapFrame(function string) bool {
+	for _, prefix := range _zapStacktracePrefixes {
+		if strings.HasPrefix(function, prefix) {
+			return true
+		}
+	}
+
+	// We can't use a prefix match here since the location of the vendor
+	// directory affects the prefix. Instead we do a contains match.
+	for _, contains := range _zapStacktraceVendorContains {
+		if strings.Contains(function, contains) {
+			return true
+		}
+	}
+
+	return false
+}
+
+type programCounters struct {
+	pcs []uintptr
+}
+
+func newProgramCounters(size int) *programCounters {
+	return &programCounters{make([]uintptr, size)}
+}
+
+func addPrefix(prefix string, ss ...string) []string {
+	withPrefix := make([]string, len(ss))
+	for i, s := range ss {
+		withPrefix[i] = prefix + s
+	}
+	return withPrefix
+}
diff --git a/vendor/go.uber.org/zap/sugar.go b/vendor/go.uber.org/zap/sugar.go
new file mode 100644
index 0000000..77ca227
--- /dev/null
+++ b/vendor/go.uber.org/zap/sugar.go
@@ -0,0 +1,304 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zap
+
+import (
+	"fmt"
+
+	"go.uber.org/zap/zapcore"
+
+	"go.uber.org/multierr"
+)
+
+const (
+	_oddNumberErrMsg    = "Ignored key without a value."
+	_nonStringKeyErrMsg = "Ignored key-value pairs with non-string keys."
+)
+
+// A SugaredLogger wraps the base Logger functionality in a slower, but less
+// verbose, API. Any Logger can be converted to a SugaredLogger with its Sugar
+// method.
+//
+// Unlike the Logger, the SugaredLogger doesn't insist on structured logging.
+// For each log level, it exposes three methods: one for loosely-typed
+// structured logging, one for println-style formatting, and one for
+// printf-style formatting. For example, SugaredLoggers can produce InfoLevel
+// output with Infow ("info with" structured context), Info, or Infof.
+type SugaredLogger struct {
+	base *Logger
+}
+
+// Desugar unwraps a SugaredLogger, exposing the original Logger. Desugaring
+// is quite inexpensive, so it's reasonable for a single application to use
+// both Loggers and SugaredLoggers, converting between them on the boundaries
+// of performance-sensitive code.
+func (s *SugaredLogger) Desugar() *Logger {
+	base := s.base.clone()
+	base.callerSkip -= 2
+	return base
+}
+
+// Named adds a sub-scope to the logger's name. See Logger.Named for details.
+func (s *SugaredLogger) Named(name string) *SugaredLogger {
+	return &SugaredLogger{base: s.base.Named(name)}
+}
+
+// With adds a variadic number of fields to the logging context. It accepts a
+// mix of strongly-typed Field objects and loosely-typed key-value pairs. When
+// processing pairs, the first element of the pair is used as the field key
+// and the second as the field value.
+//
+// For example,
+//   sugaredLogger.With(
+//     "hello", "world",
+//     "failure", errors.New("oh no"),
+//     Stack(),
+//     "count", 42,
+//     "user", User{Name: "alice"},
+//  )
+// is the equivalent of
+//   unsugared.With(
+//     String("hello", "world"),
+//     String("failure", "oh no"),
+//     Stack(),
+//     Int("count", 42),
+//     Object("user", User{Name: "alice"}),
+//   )
+//
+// Note that the keys in key-value pairs should be strings. In development,
+// passing a non-string key panics. In production, the logger is more
+// forgiving: a separate error is logged, but the key-value pair is skipped
+// and execution continues. Passing an orphaned key triggers similar behavior:
+// panics in development and errors in production.
+func (s *SugaredLogger) With(args ...interface{}) *SugaredLogger {
+	return &SugaredLogger{base: s.base.With(s.sweetenFields(args)...)}
+}
+
+// Debug uses fmt.Sprint to construct and log a message.
+func (s *SugaredLogger) Debug(args ...interface{}) {
+	s.log(DebugLevel, "", args, nil)
+}
+
+// Info uses fmt.Sprint to construct and log a message.
+func (s *SugaredLogger) Info(args ...interface{}) {
+	s.log(InfoLevel, "", args, nil)
+}
+
+// Warn uses fmt.Sprint to construct and log a message.
+func (s *SugaredLogger) Warn(args ...interface{}) {
+	s.log(WarnLevel, "", args, nil)
+}
+
+// Error uses fmt.Sprint to construct and log a message.
+func (s *SugaredLogger) Error(args ...interface{}) {
+	s.log(ErrorLevel, "", args, nil)
+}
+
+// DPanic uses fmt.Sprint to construct and log a message. In development, the
+// logger then panics. (See DPanicLevel for details.)
+func (s *SugaredLogger) DPanic(args ...interface{}) {
+	s.log(DPanicLevel, "", args, nil)
+}
+
+// Panic uses fmt.Sprint to construct and log a message, then panics.
+func (s *SugaredLogger) Panic(args ...interface{}) {
+	s.log(PanicLevel, "", args, nil)
+}
+
+// Fatal uses fmt.Sprint to construct and log a message, then calls os.Exit.
+func (s *SugaredLogger) Fatal(args ...interface{}) {
+	s.log(FatalLevel, "", args, nil)
+}
+
+// Debugf uses fmt.Sprintf to log a templated message.
+func (s *SugaredLogger) Debugf(template string, args ...interface{}) {
+	s.log(DebugLevel, template, args, nil)
+}
+
+// Infof uses fmt.Sprintf to log a templated message.
+func (s *SugaredLogger) Infof(template string, args ...interface{}) {
+	s.log(InfoLevel, template, args, nil)
+}
+
+// Warnf uses fmt.Sprintf to log a templated message.
+func (s *SugaredLogger) Warnf(template string, args ...interface{}) {
+	s.log(WarnLevel, template, args, nil)
+}
+
+// Errorf uses fmt.Sprintf to log a templated message.
+func (s *SugaredLogger) Errorf(template string, args ...interface{}) {
+	s.log(ErrorLevel, template, args, nil)
+}
+
+// DPanicf uses fmt.Sprintf to log a templated message. In development, the
+// logger then panics. (See DPanicLevel for details.)
+func (s *SugaredLogger) DPanicf(template string, args ...interface{}) {
+	s.log(DPanicLevel, template, args, nil)
+}
+
+// Panicf uses fmt.Sprintf to log a templated message, then panics.
+func (s *SugaredLogger) Panicf(template string, args ...interface{}) {
+	s.log(PanicLevel, template, args, nil)
+}
+
+// Fatalf uses fmt.Sprintf to log a templated message, then calls os.Exit.
+func (s *SugaredLogger) Fatalf(template string, args ...interface{}) {
+	s.log(FatalLevel, template, args, nil)
+}
+
+// Debugw logs a message with some additional context. The variadic key-value
+// pairs are treated as they are in With.
+//
+// When debug-level logging is disabled, this is much faster than
+//  s.With(keysAndValues).Debug(msg)
+func (s *SugaredLogger) Debugw(msg string, keysAndValues ...interface{}) {
+	s.log(DebugLevel, msg, nil, keysAndValues)
+}
+
+// Infow logs a message with some additional context. The variadic key-value
+// pairs are treated as they are in With.
+func (s *SugaredLogger) Infow(msg string, keysAndValues ...interface{}) {
+	s.log(InfoLevel, msg, nil, keysAndValues)
+}
+
+// Warnw logs a message with some additional context. The variadic key-value
+// pairs are treated as they are in With.
+func (s *SugaredLogger) Warnw(msg string, keysAndValues ...interface{}) {
+	s.log(WarnLevel, msg, nil, keysAndValues)
+}
+
+// Errorw logs a message with some additional context. The variadic key-value
+// pairs are treated as they are in With.
+func (s *SugaredLogger) Errorw(msg string, keysAndValues ...interface{}) {
+	s.log(ErrorLevel, msg, nil, keysAndValues)
+}
+
+// DPanicw logs a message with some additional context. In development, the
+// logger then panics. (See DPanicLevel for details.) The variadic key-value
+// pairs are treated as they are in With.
+func (s *SugaredLogger) DPanicw(msg string, keysAndValues ...interface{}) {
+	s.log(DPanicLevel, msg, nil, keysAndValues)
+}
+
+// Panicw logs a message with some additional context, then panics. The
+// variadic key-value pairs are treated as they are in With.
+func (s *SugaredLogger) Panicw(msg string, keysAndValues ...interface{}) {
+	s.log(PanicLevel, msg, nil, keysAndValues)
+}
+
+// Fatalw logs a message with some additional context, then calls os.Exit. The
+// variadic key-value pairs are treated as they are in With.
+func (s *SugaredLogger) Fatalw(msg string, keysAndValues ...interface{}) {
+	s.log(FatalLevel, msg, nil, keysAndValues)
+}
+
+// Sync flushes any buffered log entries.
+func (s *SugaredLogger) Sync() error {
+	return s.base.Sync()
+}
+
+func (s *SugaredLogger) log(lvl zapcore.Level, template string, fmtArgs []interface{}, context []interface{}) {
+	// If logging at this level is completely disabled, skip the overhead of
+	// string formatting.
+	if lvl < DPanicLevel && !s.base.Core().Enabled(lvl) {
+		return
+	}
+
+	// Format with Sprint, Sprintf, or neither.
+	msg := template
+	if msg == "" && len(fmtArgs) > 0 {
+		msg = fmt.Sprint(fmtArgs...)
+	} else if msg != "" && len(fmtArgs) > 0 {
+		msg = fmt.Sprintf(template, fmtArgs...)
+	}
+
+	if ce := s.base.Check(lvl, msg); ce != nil {
+		ce.Write(s.sweetenFields(context)...)
+	}
+}
+
+func (s *SugaredLogger) sweetenFields(args []interface{}) []Field {
+	if len(args) == 0 {
+		return nil
+	}
+
+	// Allocate enough space for the worst case; if users pass only structured
+	// fields, we shouldn't penalize them with extra allocations.
+	fields := make([]Field, 0, len(args))
+	var invalid invalidPairs
+
+	for i := 0; i < len(args); {
+		// This is a strongly-typed field. Consume it and move on.
+		if f, ok := args[i].(Field); ok {
+			fields = append(fields, f)
+			i++
+			continue
+		}
+
+		// Make sure this element isn't a dangling key.
+		if i == len(args)-1 {
+			s.base.DPanic(_oddNumberErrMsg, Any("ignored", args[i]))
+			break
+		}
+
+		// Consume this value and the next, treating them as a key-value pair. If the
+		// key isn't a string, add this pair to the slice of invalid pairs.
+		key, val := args[i], args[i+1]
+		if keyStr, ok := key.(string); !ok {
+			// Subsequent errors are likely, so allocate once up front.
+			if cap(invalid) == 0 {
+				invalid = make(invalidPairs, 0, len(args)/2)
+			}
+			invalid = append(invalid, invalidPair{i, key, val})
+		} else {
+			fields = append(fields, Any(keyStr, val))
+		}
+		i += 2
+	}
+
+	// If we encountered any invalid key-value pairs, log an error.
+	if len(invalid) > 0 {
+		s.base.DPanic(_nonStringKeyErrMsg, Array("invalid", invalid))
+	}
+	return fields
+}
+
+type invalidPair struct {
+	position   int
+	key, value interface{}
+}
+
+func (p invalidPair) MarshalLogObject(enc zapcore.ObjectEncoder) error {
+	enc.AddInt64("position", int64(p.position))
+	Any("key", p.key).AddTo(enc)
+	Any("value", p.value).AddTo(enc)
+	return nil
+}
+
+type invalidPairs []invalidPair
+
+func (ps invalidPairs) MarshalLogArray(enc zapcore.ArrayEncoder) error {
+	var err error
+	for i := range ps {
+		err = multierr.Append(err, enc.AppendObject(ps[i]))
+	}
+	return err
+}
diff --git a/vendor/go.uber.org/zap/time.go b/vendor/go.uber.org/zap/time.go
new file mode 100644
index 0000000..c5a1f16
--- /dev/null
+++ b/vendor/go.uber.org/zap/time.go
@@ -0,0 +1,27 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zap
+
+import "time"
+
+func timeToMillis(t time.Time) int64 {
+	return t.UnixNano() / int64(time.Millisecond)
+}
diff --git a/vendor/go.uber.org/zap/writer.go b/vendor/go.uber.org/zap/writer.go
new file mode 100644
index 0000000..86a709a
--- /dev/null
+++ b/vendor/go.uber.org/zap/writer.go
@@ -0,0 +1,99 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zap
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+
+	"go.uber.org/zap/zapcore"
+
+	"go.uber.org/multierr"
+)
+
+// Open is a high-level wrapper that takes a variadic number of URLs, opens or
+// creates each of the specified resources, and combines them into a locked
+// WriteSyncer. It also returns any error encountered and a function to close
+// any opened files.
+//
+// Passing no URLs returns a no-op WriteSyncer. Zap handles URLs without a
+// scheme and URLs with the "file" scheme. Third-party code may register
+// factories for other schemes using RegisterSink.
+//
+// URLs with the "file" scheme must use absolute paths on the local
+// filesystem. No user, password, port, fragments, or query parameters are
+// allowed, and the hostname must be empty or "localhost".
+//
+// Since it's common to write logs to the local filesystem, URLs without a
+// scheme (e.g., "/var/log/foo.log") are treated as local file paths. Without
+// a scheme, the special paths "stdout" and "stderr" are interpreted as
+// os.Stdout and os.Stderr. When specified without a scheme, relative file
+// paths also work.
+func Open(paths ...string) (zapcore.WriteSyncer, func(), error) {
+	writers, close, err := open(paths)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	writer := CombineWriteSyncers(writers...)
+	return writer, close, nil
+}
+
+func open(paths []string) ([]zapcore.WriteSyncer, func(), error) {
+	writers := make([]zapcore.WriteSyncer, 0, len(paths))
+	closers := make([]io.Closer, 0, len(paths))
+	close := func() {
+		for _, c := range closers {
+			c.Close()
+		}
+	}
+
+	var openErr error
+	for _, path := range paths {
+		sink, err := newSink(path)
+		if err != nil {
+			openErr = multierr.Append(openErr, fmt.Errorf("couldn't open sink %q: %v", path, err))
+			continue
+		}
+		writers = append(writers, sink)
+		closers = append(closers, sink)
+	}
+	if openErr != nil {
+		close()
+		return writers, nil, openErr
+	}
+
+	return writers, close, nil
+}
+
+// CombineWriteSyncers is a utility that combines multiple WriteSyncers into a
+// single, locked WriteSyncer. If no inputs are supplied, it returns a no-op
+// WriteSyncer.
+//
+// It's provided purely as a convenience; the result is no different from
+// using zapcore.NewMultiWriteSyncer and zapcore.Lock individually.
+func CombineWriteSyncers(writers ...zapcore.WriteSyncer) zapcore.WriteSyncer {
+	if len(writers) == 0 {
+		return zapcore.AddSync(ioutil.Discard)
+	}
+	return zapcore.Lock(zapcore.NewMultiWriteSyncer(writers...))
+}
diff --git a/vendor/go.uber.org/zap/zapcore/console_encoder.go b/vendor/go.uber.org/zap/zapcore/console_encoder.go
new file mode 100644
index 0000000..b787596
--- /dev/null
+++ b/vendor/go.uber.org/zap/zapcore/console_encoder.go
@@ -0,0 +1,147 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import (
+	"fmt"
+	"sync"
+
+	"go.uber.org/zap/buffer"
+	"go.uber.org/zap/internal/bufferpool"
+)
+
+var _sliceEncoderPool = sync.Pool{
+	New: func() interface{} {
+		return &sliceArrayEncoder{elems: make([]interface{}, 0, 2)}
+	},
+}
+
+func getSliceEncoder() *sliceArrayEncoder {
+	return _sliceEncoderPool.Get().(*sliceArrayEncoder)
+}
+
+func putSliceEncoder(e *sliceArrayEncoder) {
+	e.elems = e.elems[:0]
+	_sliceEncoderPool.Put(e)
+}
+
+type consoleEncoder struct {
+	*jsonEncoder
+}
+
+// NewConsoleEncoder creates an encoder whose output is designed for human -
+// rather than machine - consumption. It serializes the core log entry data
+// (message, level, timestamp, etc.) in a plain-text format and leaves the
+// structured context as JSON.
+//
+// Note that although the console encoder doesn't use the keys specified in the
+// encoder configuration, it will omit any element whose key is set to the empty
+// string.
+func NewConsoleEncoder(cfg EncoderConfig) Encoder {
+	return consoleEncoder{newJSONEncoder(cfg, true)}
+}
+
+func (c consoleEncoder) Clone() Encoder {
+	return consoleEncoder{c.jsonEncoder.Clone().(*jsonEncoder)}
+}
+
+func (c consoleEncoder) EncodeEntry(ent Entry, fields []Field) (*buffer.Buffer, error) {
+	line := bufferpool.Get()
+
+	// We don't want the entry's metadata to be quoted and escaped (if it's
+	// encoded as strings), which means that we can't use the JSON encoder. The
+	// simplest option is to use the memory encoder and fmt.Fprint.
+	//
+	// If this ever becomes a performance bottleneck, we can implement
+	// ArrayEncoder for our plain-text format.
+	arr := getSliceEncoder()
+	if c.TimeKey != "" && c.EncodeTime != nil {
+		c.EncodeTime(ent.Time, arr)
+	}
+	if c.LevelKey != "" && c.EncodeLevel != nil {
+		c.EncodeLevel(ent.Level, arr)
+	}
+	if ent.LoggerName != "" && c.NameKey != "" {
+		nameEncoder := c.EncodeName
+
+		if nameEncoder == nil {
+			// Fall back to FullNameEncoder for backward compatibility.
+			nameEncoder = FullNameEncoder
+		}
+
+		nameEncoder(ent.LoggerName, arr)
+	}
+	if ent.Caller.Defined && c.CallerKey != "" && c.EncodeCaller != nil {
+		c.EncodeCaller(ent.Caller, arr)
+	}
+	for i := range arr.elems {
+		if i > 0 {
+			line.AppendByte('\t')
+		}
+		fmt.Fprint(line, arr.elems[i])
+	}
+	putSliceEncoder(arr)
+
+	// Add the message itself.
+	if c.MessageKey != "" {
+		c.addTabIfNecessary(line)
+		line.AppendString(ent.Message)
+	}
+
+	// Add any structured context.
+	c.writeContext(line, fields)
+
+	// If there's no stacktrace key, honor that; this allows users to force
+	// single-line output.
+	if ent.Stack != "" && c.StacktraceKey != "" {
+		line.AppendByte('\n')
+		line.AppendString(ent.Stack)
+	}
+
+	if c.LineEnding != "" {
+		line.AppendString(c.LineEnding)
+	} else {
+		line.AppendString(DefaultLineEnding)
+	}
+	return line, nil
+}
+
+func (c consoleEncoder) writeContext(line *buffer.Buffer, extra []Field) {
+	context := c.jsonEncoder.Clone().(*jsonEncoder)
+	defer context.buf.Free()
+
+	addFields(context, extra)
+	context.closeOpenNamespaces()
+	if context.buf.Len() == 0 {
+		return
+	}
+
+	c.addTabIfNecessary(line)
+	line.AppendByte('{')
+	line.Write(context.buf.Bytes())
+	line.AppendByte('}')
+}
+
+func (c consoleEncoder) addTabIfNecessary(line *buffer.Buffer) {
+	if line.Len() > 0 {
+		line.AppendByte('\t')
+	}
+}
diff --git a/vendor/go.uber.org/zap/zapcore/core.go b/vendor/go.uber.org/zap/zapcore/core.go
new file mode 100644
index 0000000..a1ef8b0
--- /dev/null
+++ b/vendor/go.uber.org/zap/zapcore/core.go
@@ -0,0 +1,113 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+// Core is a minimal, fast logger interface. It's designed for library authors
+// to wrap in a more user-friendly API.
+type Core interface {
+	LevelEnabler
+
+	// With adds structured context to the Core.
+	With([]Field) Core
+	// Check determines whether the supplied Entry should be logged (using the
+	// embedded LevelEnabler and possibly some extra logic). If the entry
+	// should be logged, the Core adds itself to the CheckedEntry and returns
+	// the result.
+	//
+	// Callers must use Check before calling Write.
+	Check(Entry, *CheckedEntry) *CheckedEntry
+	// Write serializes the Entry and any Fields supplied at the log site and
+	// writes them to their destination.
+	//
+	// If called, Write should always log the Entry and Fields; it should not
+	// replicate the logic of Check.
+	Write(Entry, []Field) error
+	// Sync flushes buffered logs (if any).
+	Sync() error
+}
+
+type nopCore struct{}
+
+// NewNopCore returns a no-op Core.
+func NewNopCore() Core                                        { return nopCore{} }
+func (nopCore) Enabled(Level) bool                            { return false }
+func (n nopCore) With([]Field) Core                           { return n }
+func (nopCore) Check(_ Entry, ce *CheckedEntry) *CheckedEntry { return ce }
+func (nopCore) Write(Entry, []Field) error                    { return nil }
+func (nopCore) Sync() error                                   { return nil }
+
+// NewCore creates a Core that writes logs to a WriteSyncer.
+func NewCore(enc Encoder, ws WriteSyncer, enab LevelEnabler) Core {
+	return &ioCore{
+		LevelEnabler: enab,
+		enc:          enc,
+		out:          ws,
+	}
+}
+
+type ioCore struct {
+	LevelEnabler
+	enc Encoder
+	out WriteSyncer
+}
+
+func (c *ioCore) With(fields []Field) Core {
+	clone := c.clone()
+	addFields(clone.enc, fields)
+	return clone
+}
+
+func (c *ioCore) Check(ent Entry, ce *CheckedEntry) *CheckedEntry {
+	if c.Enabled(ent.Level) {
+		return ce.AddCore(ent, c)
+	}
+	return ce
+}
+
+func (c *ioCore) Write(ent Entry, fields []Field) error {
+	buf, err := c.enc.EncodeEntry(ent, fields)
+	if err != nil {
+		return err
+	}
+	_, err = c.out.Write(buf.Bytes())
+	buf.Free()
+	if err != nil {
+		return err
+	}
+	if ent.Level > ErrorLevel {
+		// Since we may be crashing the program, sync the output. Ignore Sync
+		// errors, pending a clean solution to issue #370.
+		c.Sync()
+	}
+	return nil
+}
+
+func (c *ioCore) Sync() error {
+	return c.out.Sync()
+}
+
+func (c *ioCore) clone() *ioCore {
+	return &ioCore{
+		LevelEnabler: c.LevelEnabler,
+		enc:          c.enc.Clone(),
+		out:          c.out,
+	}
+}
diff --git a/vendor/go.uber.org/zap/zapcore/doc.go b/vendor/go.uber.org/zap/zapcore/doc.go
new file mode 100644
index 0000000..31000e9
--- /dev/null
+++ b/vendor/go.uber.org/zap/zapcore/doc.go
@@ -0,0 +1,24 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+// Package zapcore defines and implements the low-level interfaces upon which
+// zap is built. By providing alternate implementations of these interfaces,
+// external packages can extend zap's capabilities.
+package zapcore // import "go.uber.org/zap/zapcore"
diff --git a/vendor/go.uber.org/zap/zapcore/encoder.go b/vendor/go.uber.org/zap/zapcore/encoder.go
new file mode 100644
index 0000000..f050952
--- /dev/null
+++ b/vendor/go.uber.org/zap/zapcore/encoder.go
@@ -0,0 +1,348 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import (
+	"time"
+
+	"go.uber.org/zap/buffer"
+)
+
+// DefaultLineEnding defines the default line ending when writing logs.
+// Alternate line endings specified in EncoderConfig can override this
+// behavior.
+const DefaultLineEnding = "\n"
+
+// A LevelEncoder serializes a Level to a primitive type.
+type LevelEncoder func(Level, PrimitiveArrayEncoder)
+
+// LowercaseLevelEncoder serializes a Level to a lowercase string. For example,
+// InfoLevel is serialized to "info".
+func LowercaseLevelEncoder(l Level, enc PrimitiveArrayEncoder) {
+	enc.AppendString(l.String())
+}
+
+// LowercaseColorLevelEncoder serializes a Level to a lowercase string and adds coloring.
+// For example, InfoLevel is serialized to "info" and colored blue.
+func LowercaseColorLevelEncoder(l Level, enc PrimitiveArrayEncoder) {
+	s, ok := _levelToLowercaseColorString[l]
+	if !ok {
+		s = _unknownLevelColor.Add(l.String())
+	}
+	enc.AppendString(s)
+}
+
+// CapitalLevelEncoder serializes a Level to an all-caps string. For example,
+// InfoLevel is serialized to "INFO".
+func CapitalLevelEncoder(l Level, enc PrimitiveArrayEncoder) {
+	enc.AppendString(l.CapitalString())
+}
+
+// CapitalColorLevelEncoder serializes a Level to an all-caps string and adds color.
+// For example, InfoLevel is serialized to "INFO" and colored blue.
+func CapitalColorLevelEncoder(l Level, enc PrimitiveArrayEncoder) {
+	s, ok := _levelToCapitalColorString[l]
+	if !ok {
+		s = _unknownLevelColor.Add(l.CapitalString())
+	}
+	enc.AppendString(s)
+}
+
+// UnmarshalText unmarshals text to a LevelEncoder. "capital" is unmarshaled to
+// CapitalLevelEncoder, "coloredCapital" is unmarshaled to CapitalColorLevelEncoder,
+// "colored" is unmarshaled to LowercaseColorLevelEncoder, and anything else
+// is unmarshaled to LowercaseLevelEncoder.
+func (e *LevelEncoder) UnmarshalText(text []byte) error {
+	switch string(text) {
+	case "capital":
+		*e = CapitalLevelEncoder
+	case "capitalColor":
+		*e = CapitalColorLevelEncoder
+	case "color":
+		*e = LowercaseColorLevelEncoder
+	default:
+		*e = LowercaseLevelEncoder
+	}
+	return nil
+}
+
+// A TimeEncoder serializes a time.Time to a primitive type.
+type TimeEncoder func(time.Time, PrimitiveArrayEncoder)
+
+// EpochTimeEncoder serializes a time.Time to a floating-point number of seconds
+// since the Unix epoch.
+func EpochTimeEncoder(t time.Time, enc PrimitiveArrayEncoder) {
+	nanos := t.UnixNano()
+	sec := float64(nanos) / float64(time.Second)
+	enc.AppendFloat64(sec)
+}
+
+// EpochMillisTimeEncoder serializes a time.Time to a floating-point number of
+// milliseconds since the Unix epoch.
+func EpochMillisTimeEncoder(t time.Time, enc PrimitiveArrayEncoder) {
+	nanos := t.UnixNano()
+	millis := float64(nanos) / float64(time.Millisecond)
+	enc.AppendFloat64(millis)
+}
+
+// EpochNanosTimeEncoder serializes a time.Time to an integer number of
+// nanoseconds since the Unix epoch.
+func EpochNanosTimeEncoder(t time.Time, enc PrimitiveArrayEncoder) {
+	enc.AppendInt64(t.UnixNano())
+}
+
+// ISO8601TimeEncoder serializes a time.Time to an ISO8601-formatted string
+// with millisecond precision.
+func ISO8601TimeEncoder(t time.Time, enc PrimitiveArrayEncoder) {
+	enc.AppendString(t.Format("2006-01-02T15:04:05.000Z0700"))
+}
+
+// UnmarshalText unmarshals text to a TimeEncoder. "iso8601" and "ISO8601" are
+// unmarshaled to ISO8601TimeEncoder, "millis" is unmarshaled to
+// EpochMillisTimeEncoder, and anything else is unmarshaled to EpochTimeEncoder.
+func (e *TimeEncoder) UnmarshalText(text []byte) error {
+	switch string(text) {
+	case "iso8601", "ISO8601":
+		*e = ISO8601TimeEncoder
+	case "millis":
+		*e = EpochMillisTimeEncoder
+	case "nanos":
+		*e = EpochNanosTimeEncoder
+	default:
+		*e = EpochTimeEncoder
+	}
+	return nil
+}
+
+// A DurationEncoder serializes a time.Duration to a primitive type.
+type DurationEncoder func(time.Duration, PrimitiveArrayEncoder)
+
+// SecondsDurationEncoder serializes a time.Duration to a floating-point number of seconds elapsed.
+func SecondsDurationEncoder(d time.Duration, enc PrimitiveArrayEncoder) {
+	enc.AppendFloat64(float64(d) / float64(time.Second))
+}
+
+// NanosDurationEncoder serializes a time.Duration to an integer number of
+// nanoseconds elapsed.
+func NanosDurationEncoder(d time.Duration, enc PrimitiveArrayEncoder) {
+	enc.AppendInt64(int64(d))
+}
+
+// StringDurationEncoder serializes a time.Duration using its built-in String
+// method.
+func StringDurationEncoder(d time.Duration, enc PrimitiveArrayEncoder) {
+	enc.AppendString(d.String())
+}
+
+// UnmarshalText unmarshals text to a DurationEncoder. "string" is unmarshaled
+// to StringDurationEncoder, and anything else is unmarshaled to
+// NanosDurationEncoder.
+func (e *DurationEncoder) UnmarshalText(text []byte) error {
+	switch string(text) {
+	case "string":
+		*e = StringDurationEncoder
+	case "nanos":
+		*e = NanosDurationEncoder
+	default:
+		*e = SecondsDurationEncoder
+	}
+	return nil
+}
+
+// A CallerEncoder serializes an EntryCaller to a primitive type.
+type CallerEncoder func(EntryCaller, PrimitiveArrayEncoder)
+
+// FullCallerEncoder serializes a caller in /full/path/to/package/file:line
+// format.
+func FullCallerEncoder(caller EntryCaller, enc PrimitiveArrayEncoder) {
+	// TODO: consider using a byte-oriented API to save an allocation.
+	enc.AppendString(caller.String())
+}
+
+// ShortCallerEncoder serializes a caller in package/file:line format, trimming
+// all but the final directory from the full path.
+func ShortCallerEncoder(caller EntryCaller, enc PrimitiveArrayEncoder) {
+	// TODO: consider using a byte-oriented API to save an allocation.
+	enc.AppendString(caller.TrimmedPath())
+}
+
+// UnmarshalText unmarshals text to a CallerEncoder. "full" is unmarshaled to
+// FullCallerEncoder and anything else is unmarshaled to ShortCallerEncoder.
+func (e *CallerEncoder) UnmarshalText(text []byte) error {
+	switch string(text) {
+	case "full":
+		*e = FullCallerEncoder
+	default:
+		*e = ShortCallerEncoder
+	}
+	return nil
+}
+
+// A NameEncoder serializes a period-separated logger name to a primitive
+// type.
+type NameEncoder func(string, PrimitiveArrayEncoder)
+
+// FullNameEncoder serializes the logger name as-is.
+func FullNameEncoder(loggerName string, enc PrimitiveArrayEncoder) {
+	enc.AppendString(loggerName)
+}
+
+// UnmarshalText unmarshals text to a NameEncoder. Currently, everything is
+// unmarshaled to FullNameEncoder.
+func (e *NameEncoder) UnmarshalText(text []byte) error {
+	switch string(text) {
+	case "full":
+		*e = FullNameEncoder
+	default:
+		*e = FullNameEncoder
+	}
+	return nil
+}
+
+// An EncoderConfig allows users to configure the concrete encoders supplied by
+// zapcore.
+type EncoderConfig struct {
+	// Set the keys used for each log entry. If any key is empty, that portion
+	// of the entry is omitted.
+	MessageKey    string `json:"messageKey" yaml:"messageKey"`
+	LevelKey      string `json:"levelKey" yaml:"levelKey"`
+	TimeKey       string `json:"timeKey" yaml:"timeKey"`
+	NameKey       string `json:"nameKey" yaml:"nameKey"`
+	CallerKey     string `json:"callerKey" yaml:"callerKey"`
+	StacktraceKey string `json:"stacktraceKey" yaml:"stacktraceKey"`
+	LineEnding    string `json:"lineEnding" yaml:"lineEnding"`
+	// Configure the primitive representations of common complex types. For
+	// example, some users may want all time.Times serialized as floating-point
+	// seconds since epoch, while others may prefer ISO8601 strings.
+	EncodeLevel    LevelEncoder    `json:"levelEncoder" yaml:"levelEncoder"`
+	EncodeTime     TimeEncoder     `json:"timeEncoder" yaml:"timeEncoder"`
+	EncodeDuration DurationEncoder `json:"durationEncoder" yaml:"durationEncoder"`
+	EncodeCaller   CallerEncoder   `json:"callerEncoder" yaml:"callerEncoder"`
+	// Unlike the other primitive type encoders, EncodeName is optional. The
+	// zero value falls back to FullNameEncoder.
+	EncodeName NameEncoder `json:"nameEncoder" yaml:"nameEncoder"`
+}
+
+// ObjectEncoder is a strongly-typed, encoding-agnostic interface for adding a
+// map- or struct-like object to the logging context. Like maps, ObjectEncoders
+// aren't safe for concurrent use (though typical use shouldn't require locks).
+type ObjectEncoder interface {
+	// Logging-specific marshalers.
+	AddArray(key string, marshaler ArrayMarshaler) error
+	AddObject(key string, marshaler ObjectMarshaler) error
+
+	// Built-in types.
+	AddBinary(key string, value []byte)     // for arbitrary bytes
+	AddByteString(key string, value []byte) // for UTF-8 encoded bytes
+	AddBool(key string, value bool)
+	AddComplex128(key string, value complex128)
+	AddComplex64(key string, value complex64)
+	AddDuration(key string, value time.Duration)
+	AddFloat64(key string, value float64)
+	AddFloat32(key string, value float32)
+	AddInt(key string, value int)
+	AddInt64(key string, value int64)
+	AddInt32(key string, value int32)
+	AddInt16(key string, value int16)
+	AddInt8(key string, value int8)
+	AddString(key, value string)
+	AddTime(key string, value time.Time)
+	AddUint(key string, value uint)
+	AddUint64(key string, value uint64)
+	AddUint32(key string, value uint32)
+	AddUint16(key string, value uint16)
+	AddUint8(key string, value uint8)
+	AddUintptr(key string, value uintptr)
+
+	// AddReflected uses reflection to serialize arbitrary objects, so it's slow
+	// and allocation-heavy.
+	AddReflected(key string, value interface{}) error
+	// OpenNamespace opens an isolated namespace where all subsequent fields will
+	// be added. Applications can use namespaces to prevent key collisions when
+	// injecting loggers into sub-components or third-party libraries.
+	OpenNamespace(key string)
+}
+
+// ArrayEncoder is a strongly-typed, encoding-agnostic interface for adding
+// array-like objects to the logging context. Of note, it supports mixed-type
+// arrays even though they aren't typical in Go. Like slices, ArrayEncoders
+// aren't safe for concurrent use (though typical use shouldn't require locks).
+type ArrayEncoder interface {
+	// Built-in types.
+	PrimitiveArrayEncoder
+
+	// Time-related types.
+	AppendDuration(time.Duration)
+	AppendTime(time.Time)
+
+	// Logging-specific marshalers.
+	AppendArray(ArrayMarshaler) error
+	AppendObject(ObjectMarshaler) error
+
+	// AppendReflected uses reflection to serialize arbitrary objects, so it's
+	// slow and allocation-heavy.
+	AppendReflected(value interface{}) error
+}
+
+// PrimitiveArrayEncoder is the subset of the ArrayEncoder interface that deals
+// only in Go's built-in types. It's included only so that Duration- and
+// TimeEncoders cannot trigger infinite recursion.
+type PrimitiveArrayEncoder interface {
+	// Built-in types.
+	AppendBool(bool)
+	AppendByteString([]byte) // for UTF-8 encoded bytes
+	AppendComplex128(complex128)
+	AppendComplex64(complex64)
+	AppendFloat64(float64)
+	AppendFloat32(float32)
+	AppendInt(int)
+	AppendInt64(int64)
+	AppendInt32(int32)
+	AppendInt16(int16)
+	AppendInt8(int8)
+	AppendString(string)
+	AppendUint(uint)
+	AppendUint64(uint64)
+	AppendUint32(uint32)
+	AppendUint16(uint16)
+	AppendUint8(uint8)
+	AppendUintptr(uintptr)
+}
+
+// Encoder is a format-agnostic interface for all log entry marshalers. Since
+// log encoders don't need to support the same wide range of use cases as
+// general-purpose marshalers, it's possible to make them faster and
+// lower-allocation.
+//
+// Implementations of the ObjectEncoder interface's methods can, of course,
+// freely modify the receiver. However, the Clone and EncodeEntry methods will
+// be called concurrently and shouldn't modify the receiver.
+type Encoder interface {
+	ObjectEncoder
+
+	// Clone copies the encoder, ensuring that adding fields to the copy doesn't
+	// affect the original.
+	Clone() Encoder
+
+	// EncodeEntry encodes an entry and fields, along with any accumulated
+	// context, into a byte buffer and returns it.
+	EncodeEntry(Entry, []Field) (*buffer.Buffer, error)
+}
diff --git a/vendor/go.uber.org/zap/zapcore/entry.go b/vendor/go.uber.org/zap/zapcore/entry.go
new file mode 100644
index 0000000..7d9893f
--- /dev/null
+++ b/vendor/go.uber.org/zap/zapcore/entry.go
@@ -0,0 +1,257 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import (
+	"fmt"
+	"strings"
+	"sync"
+	"time"
+
+	"go.uber.org/zap/internal/bufferpool"
+	"go.uber.org/zap/internal/exit"
+
+	"go.uber.org/multierr"
+)
+
+var (
+	_cePool = sync.Pool{New: func() interface{} {
+		// Pre-allocate some space for cores.
+		return &CheckedEntry{
+			cores: make([]Core, 4),
+		}
+	}}
+)
+
+func getCheckedEntry() *CheckedEntry {
+	ce := _cePool.Get().(*CheckedEntry)
+	ce.reset()
+	return ce
+}
+
+func putCheckedEntry(ce *CheckedEntry) {
+	if ce == nil {
+		return
+	}
+	_cePool.Put(ce)
+}
+
+// NewEntryCaller makes an EntryCaller from the return signature of
+// runtime.Caller.
+func NewEntryCaller(pc uintptr, file string, line int, ok bool) EntryCaller {
+	if !ok {
+		return EntryCaller{}
+	}
+	return EntryCaller{
+		PC:      pc,
+		File:    file,
+		Line:    line,
+		Defined: true,
+	}
+}
+
+// EntryCaller represents the caller of a logging function.
+type EntryCaller struct {
+	Defined bool
+	PC      uintptr
+	File    string
+	Line    int
+}
+
+// String returns the full path and line number of the caller.
+func (ec EntryCaller) String() string {
+	return ec.FullPath()
+}
+
+// FullPath returns a /full/path/to/package/file:line description of the
+// caller.
+func (ec EntryCaller) FullPath() string {
+	if !ec.Defined {
+		return "undefined"
+	}
+	buf := bufferpool.Get()
+	buf.AppendString(ec.File)
+	buf.AppendByte(':')
+	buf.AppendInt(int64(ec.Line))
+	caller := buf.String()
+	buf.Free()
+	return caller
+}
+
+// TrimmedPath returns a package/file:line description of the caller,
+// preserving only the leaf directory name and file name.
+func (ec EntryCaller) TrimmedPath() string {
+	if !ec.Defined {
+		return "undefined"
+	}
+	// nb. To make sure we trim the path correctly on Windows too, we
+	// counter-intuitively need to use '/' and *not* os.PathSeparator here,
+	// because the path given originates from Go stdlib, specifically
+	// runtime.Caller() which (as of Mar/17) returns forward slashes even on
+	// Windows.
+	//
+	// See https://github.com/golang/go/issues/3335
+	// and https://github.com/golang/go/issues/18151
+	//
+	// for discussion on the issue on Go side.
+	//
+	// Find the last separator.
+	//
+	idx := strings.LastIndexByte(ec.File, '/')
+	if idx == -1 {
+		return ec.FullPath()
+	}
+	// Find the penultimate separator.
+	idx = strings.LastIndexByte(ec.File[:idx], '/')
+	if idx == -1 {
+		return ec.FullPath()
+	}
+	buf := bufferpool.Get()
+	// Keep everything after the penultimate separator.
+	buf.AppendString(ec.File[idx+1:])
+	buf.AppendByte(':')
+	buf.AppendInt(int64(ec.Line))
+	caller := buf.String()
+	buf.Free()
+	return caller
+}
+
+// An Entry represents a complete log message. The entry's structured context
+// is already serialized, but the log level, time, message, and call site
+// information are available for inspection and modification.
+//
+// Entries are pooled, so any functions that accept them MUST be careful not to
+// retain references to them.
+type Entry struct {
+	Level      Level
+	Time       time.Time
+	LoggerName string
+	Message    string
+	Caller     EntryCaller
+	Stack      string
+}
+
+// CheckWriteAction indicates what action to take after a log entry is
+// processed. Actions are ordered in increasing severity.
+type CheckWriteAction uint8
+
+const (
+	// WriteThenNoop indicates that nothing special needs to be done. It's the
+	// default behavior.
+	WriteThenNoop CheckWriteAction = iota
+	// WriteThenPanic causes a panic after Write.
+	WriteThenPanic
+	// WriteThenFatal causes a fatal os.Exit after Write.
+	WriteThenFatal
+)
+
+// CheckedEntry is an Entry together with a collection of Cores that have
+// already agreed to log it.
+//
+// CheckedEntry references should be created by calling AddCore or Should on a
+// nil *CheckedEntry. References are returned to a pool after Write, and MUST
+// NOT be retained after calling their Write method.
+type CheckedEntry struct {
+	Entry
+	ErrorOutput WriteSyncer
+	dirty       bool // best-effort detection of pool misuse
+	should      CheckWriteAction
+	cores       []Core
+}
+
+func (ce *CheckedEntry) reset() {
+	ce.Entry = Entry{}
+	ce.ErrorOutput = nil
+	ce.dirty = false
+	ce.should = WriteThenNoop
+	for i := range ce.cores {
+		// don't keep references to cores
+		ce.cores[i] = nil
+	}
+	ce.cores = ce.cores[:0]
+}
+
+// Write writes the entry to the stored Cores, returns any errors, and returns
+// the CheckedEntry reference to a pool for immediate re-use. Finally, it
+// executes any required CheckWriteAction.
+func (ce *CheckedEntry) Write(fields ...Field) {
+	if ce == nil {
+		return
+	}
+
+	if ce.dirty {
+		if ce.ErrorOutput != nil {
+			// Make a best effort to detect unsafe re-use of this CheckedEntry.
+			// If the entry is dirty, log an internal error; because the
+			// CheckedEntry is being used after it was returned to the pool,
+			// the message may be an amalgamation from multiple call sites.
+			fmt.Fprintf(ce.ErrorOutput, "%v Unsafe CheckedEntry re-use near Entry %+v.\n", time.Now(), ce.Entry)
+			ce.ErrorOutput.Sync()
+		}
+		return
+	}
+	ce.dirty = true
+
+	var err error
+	for i := range ce.cores {
+		err = multierr.Append(err, ce.cores[i].Write(ce.Entry, fields))
+	}
+	if ce.ErrorOutput != nil {
+		if err != nil {
+			fmt.Fprintf(ce.ErrorOutput, "%v write error: %v\n", time.Now(), err)
+			ce.ErrorOutput.Sync()
+		}
+	}
+
+	should, msg := ce.should, ce.Message
+	putCheckedEntry(ce)
+
+	switch should {
+	case WriteThenPanic:
+		panic(msg)
+	case WriteThenFatal:
+		exit.Exit()
+	}
+}
+
+// AddCore adds a Core that has agreed to log this CheckedEntry. It's intended to be
+// used by Core.Check implementations, and is safe to call on nil CheckedEntry
+// references.
+func (ce *CheckedEntry) AddCore(ent Entry, core Core) *CheckedEntry {
+	if ce == nil {
+		ce = getCheckedEntry()
+		ce.Entry = ent
+	}
+	ce.cores = append(ce.cores, core)
+	return ce
+}
+
+// Should sets this CheckedEntry's CheckWriteAction, which controls whether a
+// Core will panic or fatal after writing this log entry. Like AddCore, it's
+// safe to call on nil CheckedEntry references.
+func (ce *CheckedEntry) Should(ent Entry, should CheckWriteAction) *CheckedEntry {
+	if ce == nil {
+		ce = getCheckedEntry()
+		ce.Entry = ent
+	}
+	ce.should = should
+	return ce
+}
diff --git a/vendor/go.uber.org/zap/zapcore/error.go b/vendor/go.uber.org/zap/zapcore/error.go
new file mode 100644
index 0000000..a67c7ba
--- /dev/null
+++ b/vendor/go.uber.org/zap/zapcore/error.go
@@ -0,0 +1,120 @@
+// Copyright (c) 2017 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import (
+	"fmt"
+	"sync"
+)
+
+// Encodes the given error into fields of an object. A field with the given
+// name is added for the error message.
+//
+// If the error implements fmt.Formatter, a field with the name ${key}Verbose
+// is also added with the full verbose error message.
+//
+// Finally, if the error implements errorGroup (from go.uber.org/multierr) or
+// causer (from github.com/pkg/errors), a ${key}Causes field is added with an
+// array of objects containing the errors this error was comprised of.
+//
+//  {
+//    "error": err.Error(),
+//    "errorVerbose": fmt.Sprintf("%+v", err),
+//    "errorCauses": [
+//      ...
+//    ],
+//  }
+func encodeError(key string, err error, enc ObjectEncoder) error {
+	basic := err.Error()
+	enc.AddString(key, basic)
+
+	switch e := err.(type) {
+	case errorGroup:
+		return enc.AddArray(key+"Causes", errArray(e.Errors()))
+	case fmt.Formatter:
+		verbose := fmt.Sprintf("%+v", e)
+		if verbose != basic {
+			// This is a rich error type, like those produced by
+			// github.com/pkg/errors.
+			enc.AddString(key+"Verbose", verbose)
+		}
+	}
+	return nil
+}
+
+type errorGroup interface {
+	// Provides read-only access to the underlying list of errors, preferably
+	// without causing any allocs.
+	Errors() []error
+}
+
+type causer interface {
+	// Provides access to the error that caused this error.
+	Cause() error
+}
+
+// Note that errArry and errArrayElem are very similar to the version
+// implemented in the top-level error.go file. We can't re-use this because
+// that would require exporting errArray as part of the zapcore API.
+
+// Encodes a list of errors using the standard error encoding logic.
+type errArray []error
+
+func (errs errArray) MarshalLogArray(arr ArrayEncoder) error {
+	for i := range errs {
+		if errs[i] == nil {
+			continue
+		}
+
+		el := newErrArrayElem(errs[i])
+		arr.AppendObject(el)
+		el.Free()
+	}
+	return nil
+}
+
+var _errArrayElemPool = sync.Pool{New: func() interface{} {
+	return &errArrayElem{}
+}}
+
+// Encodes any error into a {"error": ...} re-using the same errors logic.
+//
+// May be passed in place of an array to build a single-element array.
+type errArrayElem struct{ err error }
+
+func newErrArrayElem(err error) *errArrayElem {
+	e := _errArrayElemPool.Get().(*errArrayElem)
+	e.err = err
+	return e
+}
+
+func (e *errArrayElem) MarshalLogArray(arr ArrayEncoder) error {
+	return arr.AppendObject(e)
+}
+
+func (e *errArrayElem) MarshalLogObject(enc ObjectEncoder) error {
+	return encodeError("error", e.err, enc)
+}
+
+func (e *errArrayElem) Free() {
+	e.err = nil
+	_errArrayElemPool.Put(e)
+}
diff --git a/vendor/go.uber.org/zap/zapcore/field.go b/vendor/go.uber.org/zap/zapcore/field.go
new file mode 100644
index 0000000..6a5e33e
--- /dev/null
+++ b/vendor/go.uber.org/zap/zapcore/field.go
@@ -0,0 +1,201 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import (
+	"bytes"
+	"fmt"
+	"math"
+	"reflect"
+	"time"
+)
+
+// A FieldType indicates which member of the Field union struct should be used
+// and how it should be serialized.
+type FieldType uint8
+
+const (
+	// UnknownType is the default field type. Attempting to add it to an encoder will panic.
+	UnknownType FieldType = iota
+	// ArrayMarshalerType indicates that the field carries an ArrayMarshaler.
+	ArrayMarshalerType
+	// ObjectMarshalerType indicates that the field carries an ObjectMarshaler.
+	ObjectMarshalerType
+	// BinaryType indicates that the field carries an opaque binary blob.
+	BinaryType
+	// BoolType indicates that the field carries a bool.
+	BoolType
+	// ByteStringType indicates that the field carries UTF-8 encoded bytes.
+	ByteStringType
+	// Complex128Type indicates that the field carries a complex128.
+	Complex128Type
+	// Complex64Type indicates that the field carries a complex128.
+	Complex64Type
+	// DurationType indicates that the field carries a time.Duration.
+	DurationType
+	// Float64Type indicates that the field carries a float64.
+	Float64Type
+	// Float32Type indicates that the field carries a float32.
+	Float32Type
+	// Int64Type indicates that the field carries an int64.
+	Int64Type
+	// Int32Type indicates that the field carries an int32.
+	Int32Type
+	// Int16Type indicates that the field carries an int16.
+	Int16Type
+	// Int8Type indicates that the field carries an int8.
+	Int8Type
+	// StringType indicates that the field carries a string.
+	StringType
+	// TimeType indicates that the field carries a time.Time.
+	TimeType
+	// Uint64Type indicates that the field carries a uint64.
+	Uint64Type
+	// Uint32Type indicates that the field carries a uint32.
+	Uint32Type
+	// Uint16Type indicates that the field carries a uint16.
+	Uint16Type
+	// Uint8Type indicates that the field carries a uint8.
+	Uint8Type
+	// UintptrType indicates that the field carries a uintptr.
+	UintptrType
+	// ReflectType indicates that the field carries an interface{}, which should
+	// be serialized using reflection.
+	ReflectType
+	// NamespaceType signals the beginning of an isolated namespace. All
+	// subsequent fields should be added to the new namespace.
+	NamespaceType
+	// StringerType indicates that the field carries a fmt.Stringer.
+	StringerType
+	// ErrorType indicates that the field carries an error.
+	ErrorType
+	// SkipType indicates that the field is a no-op.
+	SkipType
+)
+
+// A Field is a marshaling operation used to add a key-value pair to a logger's
+// context. Most fields are lazily marshaled, so it's inexpensive to add fields
+// to disabled debug-level log statements.
+type Field struct {
+	Key       string
+	Type      FieldType
+	Integer   int64
+	String    string
+	Interface interface{}
+}
+
+// AddTo exports a field through the ObjectEncoder interface. It's primarily
+// useful to library authors, and shouldn't be necessary in most applications.
+func (f Field) AddTo(enc ObjectEncoder) {
+	var err error
+
+	switch f.Type {
+	case ArrayMarshalerType:
+		err = enc.AddArray(f.Key, f.Interface.(ArrayMarshaler))
+	case ObjectMarshalerType:
+		err = enc.AddObject(f.Key, f.Interface.(ObjectMarshaler))
+	case BinaryType:
+		enc.AddBinary(f.Key, f.Interface.([]byte))
+	case BoolType:
+		enc.AddBool(f.Key, f.Integer == 1)
+	case ByteStringType:
+		enc.AddByteString(f.Key, f.Interface.([]byte))
+	case Complex128Type:
+		enc.AddComplex128(f.Key, f.Interface.(complex128))
+	case Complex64Type:
+		enc.AddComplex64(f.Key, f.Interface.(complex64))
+	case DurationType:
+		enc.AddDuration(f.Key, time.Duration(f.Integer))
+	case Float64Type:
+		enc.AddFloat64(f.Key, math.Float64frombits(uint64(f.Integer)))
+	case Float32Type:
+		enc.AddFloat32(f.Key, math.Float32frombits(uint32(f.Integer)))
+	case Int64Type:
+		enc.AddInt64(f.Key, f.Integer)
+	case Int32Type:
+		enc.AddInt32(f.Key, int32(f.Integer))
+	case Int16Type:
+		enc.AddInt16(f.Key, int16(f.Integer))
+	case Int8Type:
+		enc.AddInt8(f.Key, int8(f.Integer))
+	case StringType:
+		enc.AddString(f.Key, f.String)
+	case TimeType:
+		if f.Interface != nil {
+			enc.AddTime(f.Key, time.Unix(0, f.Integer).In(f.Interface.(*time.Location)))
+		} else {
+			// Fall back to UTC if location is nil.
+			enc.AddTime(f.Key, time.Unix(0, f.Integer))
+		}
+	case Uint64Type:
+		enc.AddUint64(f.Key, uint64(f.Integer))
+	case Uint32Type:
+		enc.AddUint32(f.Key, uint32(f.Integer))
+	case Uint16Type:
+		enc.AddUint16(f.Key, uint16(f.Integer))
+	case Uint8Type:
+		enc.AddUint8(f.Key, uint8(f.Integer))
+	case UintptrType:
+		enc.AddUintptr(f.Key, uintptr(f.Integer))
+	case ReflectType:
+		err = enc.AddReflected(f.Key, f.Interface)
+	case NamespaceType:
+		enc.OpenNamespace(f.Key)
+	case StringerType:
+		enc.AddString(f.Key, f.Interface.(fmt.Stringer).String())
+	case ErrorType:
+		encodeError(f.Key, f.Interface.(error), enc)
+	case SkipType:
+		break
+	default:
+		panic(fmt.Sprintf("unknown field type: %v", f))
+	}
+
+	if err != nil {
+		enc.AddString(fmt.Sprintf("%sError", f.Key), err.Error())
+	}
+}
+
+// Equals returns whether two fields are equal. For non-primitive types such as
+// errors, marshalers, or reflect types, it uses reflect.DeepEqual.
+func (f Field) Equals(other Field) bool {
+	if f.Type != other.Type {
+		return false
+	}
+	if f.Key != other.Key {
+		return false
+	}
+
+	switch f.Type {
+	case BinaryType, ByteStringType:
+		return bytes.Equal(f.Interface.([]byte), other.Interface.([]byte))
+	case ArrayMarshalerType, ObjectMarshalerType, ErrorType, ReflectType:
+		return reflect.DeepEqual(f.Interface, other.Interface)
+	default:
+		return f == other
+	}
+}
+
+func addFields(enc ObjectEncoder, fields []Field) {
+	for i := range fields {
+		fields[i].AddTo(enc)
+	}
+}
diff --git a/vendor/go.uber.org/zap/zapcore/hook.go b/vendor/go.uber.org/zap/zapcore/hook.go
new file mode 100644
index 0000000..5db4afb
--- /dev/null
+++ b/vendor/go.uber.org/zap/zapcore/hook.go
@@ -0,0 +1,68 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import "go.uber.org/multierr"
+
+type hooked struct {
+	Core
+	funcs []func(Entry) error
+}
+
+// RegisterHooks wraps a Core and runs a collection of user-defined callback
+// hooks each time a message is logged. Execution of the callbacks is blocking.
+//
+// This offers users an easy way to register simple callbacks (e.g., metrics
+// collection) without implementing the full Core interface.
+func RegisterHooks(core Core, hooks ...func(Entry) error) Core {
+	funcs := append([]func(Entry) error{}, hooks...)
+	return &hooked{
+		Core:  core,
+		funcs: funcs,
+	}
+}
+
+func (h *hooked) Check(ent Entry, ce *CheckedEntry) *CheckedEntry {
+	// Let the wrapped Core decide whether to log this message or not. This
+	// also gives the downstream a chance to register itself directly with the
+	// CheckedEntry.
+	if downstream := h.Core.Check(ent, ce); downstream != nil {
+		return downstream.AddCore(ent, h)
+	}
+	return ce
+}
+
+func (h *hooked) With(fields []Field) Core {
+	return &hooked{
+		Core:  h.Core.With(fields),
+		funcs: h.funcs,
+	}
+}
+
+func (h *hooked) Write(ent Entry, _ []Field) error {
+	// Since our downstream had a chance to register itself directly with the
+	// CheckedMessage, we don't need to call it here.
+	var err error
+	for i := range h.funcs {
+		err = multierr.Append(err, h.funcs[i](ent))
+	}
+	return err
+}
diff --git a/vendor/go.uber.org/zap/zapcore/json_encoder.go b/vendor/go.uber.org/zap/zapcore/json_encoder.go
new file mode 100644
index 0000000..2dc67d8
--- /dev/null
+++ b/vendor/go.uber.org/zap/zapcore/json_encoder.go
@@ -0,0 +1,502 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"math"
+	"sync"
+	"time"
+	"unicode/utf8"
+
+	"go.uber.org/zap/buffer"
+	"go.uber.org/zap/internal/bufferpool"
+)
+
+// For JSON-escaping; see jsonEncoder.safeAddString below.
+const _hex = "0123456789abcdef"
+
+var _jsonPool = sync.Pool{New: func() interface{} {
+	return &jsonEncoder{}
+}}
+
+func getJSONEncoder() *jsonEncoder {
+	return _jsonPool.Get().(*jsonEncoder)
+}
+
+func putJSONEncoder(enc *jsonEncoder) {
+	if enc.reflectBuf != nil {
+		enc.reflectBuf.Free()
+	}
+	enc.EncoderConfig = nil
+	enc.buf = nil
+	enc.spaced = false
+	enc.openNamespaces = 0
+	enc.reflectBuf = nil
+	enc.reflectEnc = nil
+	_jsonPool.Put(enc)
+}
+
+type jsonEncoder struct {
+	*EncoderConfig
+	buf            *buffer.Buffer
+	spaced         bool // include spaces after colons and commas
+	openNamespaces int
+
+	// for encoding generic values by reflection
+	reflectBuf *buffer.Buffer
+	reflectEnc *json.Encoder
+}
+
+// NewJSONEncoder creates a fast, low-allocation JSON encoder. The encoder
+// appropriately escapes all field keys and values.
+//
+// Note that the encoder doesn't deduplicate keys, so it's possible to produce
+// a message like
+//   {"foo":"bar","foo":"baz"}
+// This is permitted by the JSON specification, but not encouraged. Many
+// libraries will ignore duplicate key-value pairs (typically keeping the last
+// pair) when unmarshaling, but users should attempt to avoid adding duplicate
+// keys.
+func NewJSONEncoder(cfg EncoderConfig) Encoder {
+	return newJSONEncoder(cfg, false)
+}
+
+func newJSONEncoder(cfg EncoderConfig, spaced bool) *jsonEncoder {
+	return &jsonEncoder{
+		EncoderConfig: &cfg,
+		buf:           bufferpool.Get(),
+		spaced:        spaced,
+	}
+}
+
+func (enc *jsonEncoder) AddArray(key string, arr ArrayMarshaler) error {
+	enc.addKey(key)
+	return enc.AppendArray(arr)
+}
+
+func (enc *jsonEncoder) AddObject(key string, obj ObjectMarshaler) error {
+	enc.addKey(key)
+	return enc.AppendObject(obj)
+}
+
+func (enc *jsonEncoder) AddBinary(key string, val []byte) {
+	enc.AddString(key, base64.StdEncoding.EncodeToString(val))
+}
+
+func (enc *jsonEncoder) AddByteString(key string, val []byte) {
+	enc.addKey(key)
+	enc.AppendByteString(val)
+}
+
+func (enc *jsonEncoder) AddBool(key string, val bool) {
+	enc.addKey(key)
+	enc.AppendBool(val)
+}
+
+func (enc *jsonEncoder) AddComplex128(key string, val complex128) {
+	enc.addKey(key)
+	enc.AppendComplex128(val)
+}
+
+func (enc *jsonEncoder) AddDuration(key string, val time.Duration) {
+	enc.addKey(key)
+	enc.AppendDuration(val)
+}
+
+func (enc *jsonEncoder) AddFloat64(key string, val float64) {
+	enc.addKey(key)
+	enc.AppendFloat64(val)
+}
+
+func (enc *jsonEncoder) AddInt64(key string, val int64) {
+	enc.addKey(key)
+	enc.AppendInt64(val)
+}
+
+func (enc *jsonEncoder) resetReflectBuf() {
+	if enc.reflectBuf == nil {
+		enc.reflectBuf = bufferpool.Get()
+		enc.reflectEnc = json.NewEncoder(enc.reflectBuf)
+	} else {
+		enc.reflectBuf.Reset()
+	}
+}
+
+func (enc *jsonEncoder) AddReflected(key string, obj interface{}) error {
+	enc.resetReflectBuf()
+	err := enc.reflectEnc.Encode(obj)
+	if err != nil {
+		return err
+	}
+	enc.reflectBuf.TrimNewline()
+	enc.addKey(key)
+	_, err = enc.buf.Write(enc.reflectBuf.Bytes())
+	return err
+}
+
+func (enc *jsonEncoder) OpenNamespace(key string) {
+	enc.addKey(key)
+	enc.buf.AppendByte('{')
+	enc.openNamespaces++
+}
+
+func (enc *jsonEncoder) AddString(key, val string) {
+	enc.addKey(key)
+	enc.AppendString(val)
+}
+
+func (enc *jsonEncoder) AddTime(key string, val time.Time) {
+	enc.addKey(key)
+	enc.AppendTime(val)
+}
+
+func (enc *jsonEncoder) AddUint64(key string, val uint64) {
+	enc.addKey(key)
+	enc.AppendUint64(val)
+}
+
+func (enc *jsonEncoder) AppendArray(arr ArrayMarshaler) error {
+	enc.addElementSeparator()
+	enc.buf.AppendByte('[')
+	err := arr.MarshalLogArray(enc)
+	enc.buf.AppendByte(']')
+	return err
+}
+
+func (enc *jsonEncoder) AppendObject(obj ObjectMarshaler) error {
+	enc.addElementSeparator()
+	enc.buf.AppendByte('{')
+	err := obj.MarshalLogObject(enc)
+	enc.buf.AppendByte('}')
+	return err
+}
+
+func (enc *jsonEncoder) AppendBool(val bool) {
+	enc.addElementSeparator()
+	enc.buf.AppendBool(val)
+}
+
+func (enc *jsonEncoder) AppendByteString(val []byte) {
+	enc.addElementSeparator()
+	enc.buf.AppendByte('"')
+	enc.safeAddByteString(val)
+	enc.buf.AppendByte('"')
+}
+
+func (enc *jsonEncoder) AppendComplex128(val complex128) {
+	enc.addElementSeparator()
+	// Cast to a platform-independent, fixed-size type.
+	r, i := float64(real(val)), float64(imag(val))
+	enc.buf.AppendByte('"')
+	// Because we're always in a quoted string, we can use strconv without
+	// special-casing NaN and +/-Inf.
+	enc.buf.AppendFloat(r, 64)
+	enc.buf.AppendByte('+')
+	enc.buf.AppendFloat(i, 64)
+	enc.buf.AppendByte('i')
+	enc.buf.AppendByte('"')
+}
+
+func (enc *jsonEncoder) AppendDuration(val time.Duration) {
+	cur := enc.buf.Len()
+	enc.EncodeDuration(val, enc)
+	if cur == enc.buf.Len() {
+		// User-supplied EncodeDuration is a no-op. Fall back to nanoseconds to keep
+		// JSON valid.
+		enc.AppendInt64(int64(val))
+	}
+}
+
+func (enc *jsonEncoder) AppendInt64(val int64) {
+	enc.addElementSeparator()
+	enc.buf.AppendInt(val)
+}
+
+func (enc *jsonEncoder) AppendReflected(val interface{}) error {
+	enc.resetReflectBuf()
+	err := enc.reflectEnc.Encode(val)
+	if err != nil {
+		return err
+	}
+	enc.reflectBuf.TrimNewline()
+	enc.addElementSeparator()
+	_, err = enc.buf.Write(enc.reflectBuf.Bytes())
+	return err
+}
+
+func (enc *jsonEncoder) AppendString(val string) {
+	enc.addElementSeparator()
+	enc.buf.AppendByte('"')
+	enc.safeAddString(val)
+	enc.buf.AppendByte('"')
+}
+
+func (enc *jsonEncoder) AppendTime(val time.Time) {
+	cur := enc.buf.Len()
+	enc.EncodeTime(val, enc)
+	if cur == enc.buf.Len() {
+		// User-supplied EncodeTime is a no-op. Fall back to nanos since epoch to keep
+		// output JSON valid.
+		enc.AppendInt64(val.UnixNano())
+	}
+}
+
+func (enc *jsonEncoder) AppendUint64(val uint64) {
+	enc.addElementSeparator()
+	enc.buf.AppendUint(val)
+}
+
+func (enc *jsonEncoder) AddComplex64(k string, v complex64) { enc.AddComplex128(k, complex128(v)) }
+func (enc *jsonEncoder) AddFloat32(k string, v float32)     { enc.AddFloat64(k, float64(v)) }
+func (enc *jsonEncoder) AddInt(k string, v int)             { enc.AddInt64(k, int64(v)) }
+func (enc *jsonEncoder) AddInt32(k string, v int32)         { enc.AddInt64(k, int64(v)) }
+func (enc *jsonEncoder) AddInt16(k string, v int16)         { enc.AddInt64(k, int64(v)) }
+func (enc *jsonEncoder) AddInt8(k string, v int8)           { enc.AddInt64(k, int64(v)) }
+func (enc *jsonEncoder) AddUint(k string, v uint)           { enc.AddUint64(k, uint64(v)) }
+func (enc *jsonEncoder) AddUint32(k string, v uint32)       { enc.AddUint64(k, uint64(v)) }
+func (enc *jsonEncoder) AddUint16(k string, v uint16)       { enc.AddUint64(k, uint64(v)) }
+func (enc *jsonEncoder) AddUint8(k string, v uint8)         { enc.AddUint64(k, uint64(v)) }
+func (enc *jsonEncoder) AddUintptr(k string, v uintptr)     { enc.AddUint64(k, uint64(v)) }
+func (enc *jsonEncoder) AppendComplex64(v complex64)        { enc.AppendComplex128(complex128(v)) }
+func (enc *jsonEncoder) AppendFloat64(v float64)            { enc.appendFloat(v, 64) }
+func (enc *jsonEncoder) AppendFloat32(v float32)            { enc.appendFloat(float64(v), 32) }
+func (enc *jsonEncoder) AppendInt(v int)                    { enc.AppendInt64(int64(v)) }
+func (enc *jsonEncoder) AppendInt32(v int32)                { enc.AppendInt64(int64(v)) }
+func (enc *jsonEncoder) AppendInt16(v int16)                { enc.AppendInt64(int64(v)) }
+func (enc *jsonEncoder) AppendInt8(v int8)                  { enc.AppendInt64(int64(v)) }
+func (enc *jsonEncoder) AppendUint(v uint)                  { enc.AppendUint64(uint64(v)) }
+func (enc *jsonEncoder) AppendUint32(v uint32)              { enc.AppendUint64(uint64(v)) }
+func (enc *jsonEncoder) AppendUint16(v uint16)              { enc.AppendUint64(uint64(v)) }
+func (enc *jsonEncoder) AppendUint8(v uint8)                { enc.AppendUint64(uint64(v)) }
+func (enc *jsonEncoder) AppendUintptr(v uintptr)            { enc.AppendUint64(uint64(v)) }
+
+func (enc *jsonEncoder) Clone() Encoder {
+	clone := enc.clone()
+	clone.buf.Write(enc.buf.Bytes())
+	return clone
+}
+
+func (enc *jsonEncoder) clone() *jsonEncoder {
+	clone := getJSONEncoder()
+	clone.EncoderConfig = enc.EncoderConfig
+	clone.spaced = enc.spaced
+	clone.openNamespaces = enc.openNamespaces
+	clone.buf = bufferpool.Get()
+	return clone
+}
+
+func (enc *jsonEncoder) EncodeEntry(ent Entry, fields []Field) (*buffer.Buffer, error) {
+	final := enc.clone()
+	final.buf.AppendByte('{')
+
+	if final.LevelKey != "" {
+		final.addKey(final.LevelKey)
+		cur := final.buf.Len()
+		final.EncodeLevel(ent.Level, final)
+		if cur == final.buf.Len() {
+			// User-supplied EncodeLevel was a no-op. Fall back to strings to keep
+			// output JSON valid.
+			final.AppendString(ent.Level.String())
+		}
+	}
+	if final.TimeKey != "" {
+		final.AddTime(final.TimeKey, ent.Time)
+	}
+	if ent.LoggerName != "" && final.NameKey != "" {
+		final.addKey(final.NameKey)
+		cur := final.buf.Len()
+		nameEncoder := final.EncodeName
+
+		// if no name encoder provided, fall back to FullNameEncoder for backwards
+		// compatibility
+		if nameEncoder == nil {
+			nameEncoder = FullNameEncoder
+		}
+
+		nameEncoder(ent.LoggerName, final)
+		if cur == final.buf.Len() {
+			// User-supplied EncodeName was a no-op. Fall back to strings to
+			// keep output JSON valid.
+			final.AppendString(ent.LoggerName)
+		}
+	}
+	if ent.Caller.Defined && final.CallerKey != "" {
+		final.addKey(final.CallerKey)
+		cur := final.buf.Len()
+		final.EncodeCaller(ent.Caller, final)
+		if cur == final.buf.Len() {
+			// User-supplied EncodeCaller was a no-op. Fall back to strings to
+			// keep output JSON valid.
+			final.AppendString(ent.Caller.String())
+		}
+	}
+	if final.MessageKey != "" {
+		final.addKey(enc.MessageKey)
+		final.AppendString(ent.Message)
+	}
+	if enc.buf.Len() > 0 {
+		final.addElementSeparator()
+		final.buf.Write(enc.buf.Bytes())
+	}
+	addFields(final, fields)
+	final.closeOpenNamespaces()
+	if ent.Stack != "" && final.StacktraceKey != "" {
+		final.AddString(final.StacktraceKey, ent.Stack)
+	}
+	final.buf.AppendByte('}')
+	if final.LineEnding != "" {
+		final.buf.AppendString(final.LineEnding)
+	} else {
+		final.buf.AppendString(DefaultLineEnding)
+	}
+
+	ret := final.buf
+	putJSONEncoder(final)
+	return ret, nil
+}
+
+func (enc *jsonEncoder) truncate() {
+	enc.buf.Reset()
+}
+
+func (enc *jsonEncoder) closeOpenNamespaces() {
+	for i := 0; i < enc.openNamespaces; i++ {
+		enc.buf.AppendByte('}')
+	}
+}
+
+func (enc *jsonEncoder) addKey(key string) {
+	enc.addElementSeparator()
+	enc.buf.AppendByte('"')
+	enc.safeAddString(key)
+	enc.buf.AppendByte('"')
+	enc.buf.AppendByte(':')
+	if enc.spaced {
+		enc.buf.AppendByte(' ')
+	}
+}
+
+func (enc *jsonEncoder) addElementSeparator() {
+	last := enc.buf.Len() - 1
+	if last < 0 {
+		return
+	}
+	switch enc.buf.Bytes()[last] {
+	case '{', '[', ':', ',', ' ':
+		return
+	default:
+		enc.buf.AppendByte(',')
+		if enc.spaced {
+			enc.buf.AppendByte(' ')
+		}
+	}
+}
+
+func (enc *jsonEncoder) appendFloat(val float64, bitSize int) {
+	enc.addElementSeparator()
+	switch {
+	case math.IsNaN(val):
+		enc.buf.AppendString(`"NaN"`)
+	case math.IsInf(val, 1):
+		enc.buf.AppendString(`"+Inf"`)
+	case math.IsInf(val, -1):
+		enc.buf.AppendString(`"-Inf"`)
+	default:
+		enc.buf.AppendFloat(val, bitSize)
+	}
+}
+
+// safeAddString JSON-escapes a string and appends it to the internal buffer.
+// Unlike the standard library's encoder, it doesn't attempt to protect the
+// user from browser vulnerabilities or JSONP-related problems.
+func (enc *jsonEncoder) safeAddString(s string) {
+	for i := 0; i < len(s); {
+		if enc.tryAddRuneSelf(s[i]) {
+			i++
+			continue
+		}
+		r, size := utf8.DecodeRuneInString(s[i:])
+		if enc.tryAddRuneError(r, size) {
+			i++
+			continue
+		}
+		enc.buf.AppendString(s[i : i+size])
+		i += size
+	}
+}
+
+// safeAddByteString is no-alloc equivalent of safeAddString(string(s)) for s []byte.
+func (enc *jsonEncoder) safeAddByteString(s []byte) {
+	for i := 0; i < len(s); {
+		if enc.tryAddRuneSelf(s[i]) {
+			i++
+			continue
+		}
+		r, size := utf8.DecodeRune(s[i:])
+		if enc.tryAddRuneError(r, size) {
+			i++
+			continue
+		}
+		enc.buf.Write(s[i : i+size])
+		i += size
+	}
+}
+
+// tryAddRuneSelf appends b if it is valid UTF-8 character represented in a single byte.
+func (enc *jsonEncoder) tryAddRuneSelf(b byte) bool {
+	if b >= utf8.RuneSelf {
+		return false
+	}
+	if 0x20 <= b && b != '\\' && b != '"' {
+		enc.buf.AppendByte(b)
+		return true
+	}
+	switch b {
+	case '\\', '"':
+		enc.buf.AppendByte('\\')
+		enc.buf.AppendByte(b)
+	case '\n':
+		enc.buf.AppendByte('\\')
+		enc.buf.AppendByte('n')
+	case '\r':
+		enc.buf.AppendByte('\\')
+		enc.buf.AppendByte('r')
+	case '\t':
+		enc.buf.AppendByte('\\')
+		enc.buf.AppendByte('t')
+	default:
+		// Encode bytes < 0x20, except for the escape sequences above.
+		enc.buf.AppendString(`\u00`)
+		enc.buf.AppendByte(_hex[b>>4])
+		enc.buf.AppendByte(_hex[b&0xF])
+	}
+	return true
+}
+
+func (enc *jsonEncoder) tryAddRuneError(r rune, size int) bool {
+	if r == utf8.RuneError && size == 1 {
+		enc.buf.AppendString(`\ufffd`)
+		return true
+	}
+	return false
+}
diff --git a/vendor/go.uber.org/zap/zapcore/level.go b/vendor/go.uber.org/zap/zapcore/level.go
new file mode 100644
index 0000000..e575c9f
--- /dev/null
+++ b/vendor/go.uber.org/zap/zapcore/level.go
@@ -0,0 +1,175 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+)
+
+var errUnmarshalNilLevel = errors.New("can't unmarshal a nil *Level")
+
+// A Level is a logging priority. Higher levels are more important.
+type Level int8
+
+const (
+	// DebugLevel logs are typically voluminous, and are usually disabled in
+	// production.
+	DebugLevel Level = iota - 1
+	// InfoLevel is the default logging priority.
+	InfoLevel
+	// WarnLevel logs are more important than Info, but don't need individual
+	// human review.
+	WarnLevel
+	// ErrorLevel logs are high-priority. If an application is running smoothly,
+	// it shouldn't generate any error-level logs.
+	ErrorLevel
+	// DPanicLevel logs are particularly important errors. In development the
+	// logger panics after writing the message.
+	DPanicLevel
+	// PanicLevel logs a message, then panics.
+	PanicLevel
+	// FatalLevel logs a message, then calls os.Exit(1).
+	FatalLevel
+
+	_minLevel = DebugLevel
+	_maxLevel = FatalLevel
+)
+
+// String returns a lower-case ASCII representation of the log level.
+func (l Level) String() string {
+	switch l {
+	case DebugLevel:
+		return "debug"
+	case InfoLevel:
+		return "info"
+	case WarnLevel:
+		return "warn"
+	case ErrorLevel:
+		return "error"
+	case DPanicLevel:
+		return "dpanic"
+	case PanicLevel:
+		return "panic"
+	case FatalLevel:
+		return "fatal"
+	default:
+		return fmt.Sprintf("Level(%d)", l)
+	}
+}
+
+// CapitalString returns an all-caps ASCII representation of the log level.
+func (l Level) CapitalString() string {
+	// Printing levels in all-caps is common enough that we should export this
+	// functionality.
+	switch l {
+	case DebugLevel:
+		return "DEBUG"
+	case InfoLevel:
+		return "INFO"
+	case WarnLevel:
+		return "WARN"
+	case ErrorLevel:
+		return "ERROR"
+	case DPanicLevel:
+		return "DPANIC"
+	case PanicLevel:
+		return "PANIC"
+	case FatalLevel:
+		return "FATAL"
+	default:
+		return fmt.Sprintf("LEVEL(%d)", l)
+	}
+}
+
+// MarshalText marshals the Level to text. Note that the text representation
+// drops the -Level suffix (see example).
+func (l Level) MarshalText() ([]byte, error) {
+	return []byte(l.String()), nil
+}
+
+// UnmarshalText unmarshals text to a level. Like MarshalText, UnmarshalText
+// expects the text representation of a Level to drop the -Level suffix (see
+// example).
+//
+// In particular, this makes it easy to configure logging levels using YAML,
+// TOML, or JSON files.
+func (l *Level) UnmarshalText(text []byte) error {
+	if l == nil {
+		return errUnmarshalNilLevel
+	}
+	if !l.unmarshalText(text) && !l.unmarshalText(bytes.ToLower(text)) {
+		return fmt.Errorf("unrecognized level: %q", text)
+	}
+	return nil
+}
+
+func (l *Level) unmarshalText(text []byte) bool {
+	switch string(text) {
+	case "debug", "DEBUG":
+		*l = DebugLevel
+	case "info", "INFO", "": // make the zero value useful
+		*l = InfoLevel
+	case "warn", "WARN":
+		*l = WarnLevel
+	case "error", "ERROR":
+		*l = ErrorLevel
+	case "dpanic", "DPANIC":
+		*l = DPanicLevel
+	case "panic", "PANIC":
+		*l = PanicLevel
+	case "fatal", "FATAL":
+		*l = FatalLevel
+	default:
+		return false
+	}
+	return true
+}
+
+// Set sets the level for the flag.Value interface.
+func (l *Level) Set(s string) error {
+	return l.UnmarshalText([]byte(s))
+}
+
+// Get gets the level for the flag.Getter interface.
+func (l *Level) Get() interface{} {
+	return *l
+}
+
+// Enabled returns true if the given level is at or above this level.
+func (l Level) Enabled(lvl Level) bool {
+	return lvl >= l
+}
+
+// LevelEnabler decides whether a given logging level is enabled when logging a
+// message.
+//
+// Enablers are intended to be used to implement deterministic filters;
+// concerns like sampling are better implemented as a Core.
+//
+// Each concrete Level value implements a static LevelEnabler which returns
+// true for itself and all higher logging levels. For example WarnLevel.Enabled()
+// will return true for WarnLevel, ErrorLevel, DPanicLevel, PanicLevel, and
+// FatalLevel, but return false for InfoLevel and DebugLevel.
+type LevelEnabler interface {
+	Enabled(Level) bool
+}
diff --git a/vendor/go.uber.org/zap/zapcore/level_strings.go b/vendor/go.uber.org/zap/zapcore/level_strings.go
new file mode 100644
index 0000000..7af8dad
--- /dev/null
+++ b/vendor/go.uber.org/zap/zapcore/level_strings.go
@@ -0,0 +1,46 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import "go.uber.org/zap/internal/color"
+
+var (
+	_levelToColor = map[Level]color.Color{
+		DebugLevel:  color.Magenta,
+		InfoLevel:   color.Blue,
+		WarnLevel:   color.Yellow,
+		ErrorLevel:  color.Red,
+		DPanicLevel: color.Red,
+		PanicLevel:  color.Red,
+		FatalLevel:  color.Red,
+	}
+	_unknownLevelColor = color.Red
+
+	_levelToLowercaseColorString = make(map[Level]string, len(_levelToColor))
+	_levelToCapitalColorString   = make(map[Level]string, len(_levelToColor))
+)
+
+func init() {
+	for level, color := range _levelToColor {
+		_levelToLowercaseColorString[level] = color.Add(level.String())
+		_levelToCapitalColorString[level] = color.Add(level.CapitalString())
+	}
+}
diff --git a/vendor/go.uber.org/zap/zapcore/marshaler.go b/vendor/go.uber.org/zap/zapcore/marshaler.go
new file mode 100644
index 0000000..2627a65
--- /dev/null
+++ b/vendor/go.uber.org/zap/zapcore/marshaler.go
@@ -0,0 +1,53 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+// ObjectMarshaler allows user-defined types to efficiently add themselves to the
+// logging context, and to selectively omit information which shouldn't be
+// included in logs (e.g., passwords).
+type ObjectMarshaler interface {
+	MarshalLogObject(ObjectEncoder) error
+}
+
+// ObjectMarshalerFunc is a type adapter that turns a function into an
+// ObjectMarshaler.
+type ObjectMarshalerFunc func(ObjectEncoder) error
+
+// MarshalLogObject calls the underlying function.
+func (f ObjectMarshalerFunc) MarshalLogObject(enc ObjectEncoder) error {
+	return f(enc)
+}
+
+// ArrayMarshaler allows user-defined types to efficiently add themselves to the
+// logging context, and to selectively omit information which shouldn't be
+// included in logs (e.g., passwords).
+type ArrayMarshaler interface {
+	MarshalLogArray(ArrayEncoder) error
+}
+
+// ArrayMarshalerFunc is a type adapter that turns a function into an
+// ArrayMarshaler.
+type ArrayMarshalerFunc func(ArrayEncoder) error
+
+// MarshalLogArray calls the underlying function.
+func (f ArrayMarshalerFunc) MarshalLogArray(enc ArrayEncoder) error {
+	return f(enc)
+}
diff --git a/vendor/go.uber.org/zap/zapcore/memory_encoder.go b/vendor/go.uber.org/zap/zapcore/memory_encoder.go
new file mode 100644
index 0000000..6ef85b0
--- /dev/null
+++ b/vendor/go.uber.org/zap/zapcore/memory_encoder.go
@@ -0,0 +1,179 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import "time"
+
+// MapObjectEncoder is an ObjectEncoder backed by a simple
+// map[string]interface{}. It's not fast enough for production use, but it's
+// helpful in tests.
+type MapObjectEncoder struct {
+	// Fields contains the entire encoded log context.
+	Fields map[string]interface{}
+	// cur is a pointer to the namespace we're currently writing to.
+	cur map[string]interface{}
+}
+
+// NewMapObjectEncoder creates a new map-backed ObjectEncoder.
+func NewMapObjectEncoder() *MapObjectEncoder {
+	m := make(map[string]interface{})
+	return &MapObjectEncoder{
+		Fields: m,
+		cur:    m,
+	}
+}
+
+// AddArray implements ObjectEncoder.
+func (m *MapObjectEncoder) AddArray(key string, v ArrayMarshaler) error {
+	arr := &sliceArrayEncoder{elems: make([]interface{}, 0)}
+	err := v.MarshalLogArray(arr)
+	m.cur[key] = arr.elems
+	return err
+}
+
+// AddObject implements ObjectEncoder.
+func (m *MapObjectEncoder) AddObject(k string, v ObjectMarshaler) error {
+	newMap := NewMapObjectEncoder()
+	m.cur[k] = newMap.Fields
+	return v.MarshalLogObject(newMap)
+}
+
+// AddBinary implements ObjectEncoder.
+func (m *MapObjectEncoder) AddBinary(k string, v []byte) { m.cur[k] = v }
+
+// AddByteString implements ObjectEncoder.
+func (m *MapObjectEncoder) AddByteString(k string, v []byte) { m.cur[k] = string(v) }
+
+// AddBool implements ObjectEncoder.
+func (m *MapObjectEncoder) AddBool(k string, v bool) { m.cur[k] = v }
+
+// AddDuration implements ObjectEncoder.
+func (m MapObjectEncoder) AddDuration(k string, v time.Duration) { m.cur[k] = v }
+
+// AddComplex128 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddComplex128(k string, v complex128) { m.cur[k] = v }
+
+// AddComplex64 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddComplex64(k string, v complex64) { m.cur[k] = v }
+
+// AddFloat64 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddFloat64(k string, v float64) { m.cur[k] = v }
+
+// AddFloat32 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddFloat32(k string, v float32) { m.cur[k] = v }
+
+// AddInt implements ObjectEncoder.
+func (m *MapObjectEncoder) AddInt(k string, v int) { m.cur[k] = v }
+
+// AddInt64 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddInt64(k string, v int64) { m.cur[k] = v }
+
+// AddInt32 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddInt32(k string, v int32) { m.cur[k] = v }
+
+// AddInt16 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddInt16(k string, v int16) { m.cur[k] = v }
+
+// AddInt8 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddInt8(k string, v int8) { m.cur[k] = v }
+
+// AddString implements ObjectEncoder.
+func (m *MapObjectEncoder) AddString(k string, v string) { m.cur[k] = v }
+
+// AddTime implements ObjectEncoder.
+func (m MapObjectEncoder) AddTime(k string, v time.Time) { m.cur[k] = v }
+
+// AddUint implements ObjectEncoder.
+func (m *MapObjectEncoder) AddUint(k string, v uint) { m.cur[k] = v }
+
+// AddUint64 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddUint64(k string, v uint64) { m.cur[k] = v }
+
+// AddUint32 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddUint32(k string, v uint32) { m.cur[k] = v }
+
+// AddUint16 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddUint16(k string, v uint16) { m.cur[k] = v }
+
+// AddUint8 implements ObjectEncoder.
+func (m *MapObjectEncoder) AddUint8(k string, v uint8) { m.cur[k] = v }
+
+// AddUintptr implements ObjectEncoder.
+func (m *MapObjectEncoder) AddUintptr(k string, v uintptr) { m.cur[k] = v }
+
+// AddReflected implements ObjectEncoder.
+func (m *MapObjectEncoder) AddReflected(k string, v interface{}) error {
+	m.cur[k] = v
+	return nil
+}
+
+// OpenNamespace implements ObjectEncoder.
+func (m *MapObjectEncoder) OpenNamespace(k string) {
+	ns := make(map[string]interface{})
+	m.cur[k] = ns
+	m.cur = ns
+}
+
+// sliceArrayEncoder is an ArrayEncoder backed by a simple []interface{}. Like
+// the MapObjectEncoder, it's not designed for production use.
+type sliceArrayEncoder struct {
+	elems []interface{}
+}
+
+func (s *sliceArrayEncoder) AppendArray(v ArrayMarshaler) error {
+	enc := &sliceArrayEncoder{}
+	err := v.MarshalLogArray(enc)
+	s.elems = append(s.elems, enc.elems)
+	return err
+}
+
+func (s *sliceArrayEncoder) AppendObject(v ObjectMarshaler) error {
+	m := NewMapObjectEncoder()
+	err := v.MarshalLogObject(m)
+	s.elems = append(s.elems, m.Fields)
+	return err
+}
+
+func (s *sliceArrayEncoder) AppendReflected(v interface{}) error {
+	s.elems = append(s.elems, v)
+	return nil
+}
+
+func (s *sliceArrayEncoder) AppendBool(v bool)              { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendByteString(v []byte)      { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendComplex128(v complex128)  { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendComplex64(v complex64)    { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendDuration(v time.Duration) { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendFloat64(v float64)        { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendFloat32(v float32)        { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendInt(v int)                { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendInt64(v int64)            { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendInt32(v int32)            { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendInt16(v int16)            { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendInt8(v int8)              { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendString(v string)          { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendTime(v time.Time)         { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendUint(v uint)              { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendUint64(v uint64)          { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendUint32(v uint32)          { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendUint16(v uint16)          { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendUint8(v uint8)            { s.elems = append(s.elems, v) }
+func (s *sliceArrayEncoder) AppendUintptr(v uintptr)        { s.elems = append(s.elems, v) }
diff --git a/vendor/go.uber.org/zap/zapcore/sampler.go b/vendor/go.uber.org/zap/zapcore/sampler.go
new file mode 100644
index 0000000..e316418
--- /dev/null
+++ b/vendor/go.uber.org/zap/zapcore/sampler.go
@@ -0,0 +1,134 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import (
+	"time"
+
+	"go.uber.org/atomic"
+)
+
+const (
+	_numLevels        = _maxLevel - _minLevel + 1
+	_countersPerLevel = 4096
+)
+
+type counter struct {
+	resetAt atomic.Int64
+	counter atomic.Uint64
+}
+
+type counters [_numLevels][_countersPerLevel]counter
+
+func newCounters() *counters {
+	return &counters{}
+}
+
+func (cs *counters) get(lvl Level, key string) *counter {
+	i := lvl - _minLevel
+	j := fnv32a(key) % _countersPerLevel
+	return &cs[i][j]
+}
+
+// fnv32a, adapted from "hash/fnv", but without a []byte(string) alloc
+func fnv32a(s string) uint32 {
+	const (
+		offset32 = 2166136261
+		prime32  = 16777619
+	)
+	hash := uint32(offset32)
+	for i := 0; i < len(s); i++ {
+		hash ^= uint32(s[i])
+		hash *= prime32
+	}
+	return hash
+}
+
+func (c *counter) IncCheckReset(t time.Time, tick time.Duration) uint64 {
+	tn := t.UnixNano()
+	resetAfter := c.resetAt.Load()
+	if resetAfter > tn {
+		return c.counter.Inc()
+	}
+
+	c.counter.Store(1)
+
+	newResetAfter := tn + tick.Nanoseconds()
+	if !c.resetAt.CAS(resetAfter, newResetAfter) {
+		// We raced with another goroutine trying to reset, and it also reset
+		// the counter to 1, so we need to reincrement the counter.
+		return c.counter.Inc()
+	}
+
+	return 1
+}
+
+type sampler struct {
+	Core
+
+	counts            *counters
+	tick              time.Duration
+	first, thereafter uint64
+}
+
+// NewSampler creates a Core that samples incoming entries, which caps the CPU
+// and I/O load of logging while attempting to preserve a representative subset
+// of your logs.
+//
+// Zap samples by logging the first N entries with a given level and message
+// each tick. If more Entries with the same level and message are seen during
+// the same interval, every Mth message is logged and the rest are dropped.
+//
+// Keep in mind that zap's sampling implementation is optimized for speed over
+// absolute precision; under load, each tick may be slightly over- or
+// under-sampled.
+func NewSampler(core Core, tick time.Duration, first, thereafter int) Core {
+	return &sampler{
+		Core:       core,
+		tick:       tick,
+		counts:     newCounters(),
+		first:      uint64(first),
+		thereafter: uint64(thereafter),
+	}
+}
+
+func (s *sampler) With(fields []Field) Core {
+	return &sampler{
+		Core:       s.Core.With(fields),
+		tick:       s.tick,
+		counts:     s.counts,
+		first:      s.first,
+		thereafter: s.thereafter,
+	}
+}
+
+func (s *sampler) Check(ent Entry, ce *CheckedEntry) *CheckedEntry {
+	if !s.Enabled(ent.Level) {
+		return ce
+	}
+
+	counter := s.counts.get(ent.Level, ent.Message)
+	n := counter.IncCheckReset(ent.Time, s.tick)
+	if n > s.first && (n-s.first)%s.thereafter != 0 {
+		return ce
+	}
+	return s.Core.Check(ent, ce)
+}
diff --git a/vendor/go.uber.org/zap/zapcore/tee.go b/vendor/go.uber.org/zap/zapcore/tee.go
new file mode 100644
index 0000000..07a32ee
--- /dev/null
+++ b/vendor/go.uber.org/zap/zapcore/tee.go
@@ -0,0 +1,81 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import "go.uber.org/multierr"
+
+type multiCore []Core
+
+// NewTee creates a Core that duplicates log entries into two or more
+// underlying Cores.
+//
+// Calling it with a single Core returns the input unchanged, and calling
+// it with no input returns a no-op Core.
+func NewTee(cores ...Core) Core {
+	switch len(cores) {
+	case 0:
+		return NewNopCore()
+	case 1:
+		return cores[0]
+	default:
+		return multiCore(cores)
+	}
+}
+
+func (mc multiCore) With(fields []Field) Core {
+	clone := make(multiCore, len(mc))
+	for i := range mc {
+		clone[i] = mc[i].With(fields)
+	}
+	return clone
+}
+
+func (mc multiCore) Enabled(lvl Level) bool {
+	for i := range mc {
+		if mc[i].Enabled(lvl) {
+			return true
+		}
+	}
+	return false
+}
+
+func (mc multiCore) Check(ent Entry, ce *CheckedEntry) *CheckedEntry {
+	for i := range mc {
+		ce = mc[i].Check(ent, ce)
+	}
+	return ce
+}
+
+func (mc multiCore) Write(ent Entry, fields []Field) error {
+	var err error
+	for i := range mc {
+		err = multierr.Append(err, mc[i].Write(ent, fields))
+	}
+	return err
+}
+
+func (mc multiCore) Sync() error {
+	var err error
+	for i := range mc {
+		err = multierr.Append(err, mc[i].Sync())
+	}
+	return err
+}
diff --git a/vendor/go.uber.org/zap/zapcore/write_syncer.go b/vendor/go.uber.org/zap/zapcore/write_syncer.go
new file mode 100644
index 0000000..209e25f
--- /dev/null
+++ b/vendor/go.uber.org/zap/zapcore/write_syncer.go
@@ -0,0 +1,123 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import (
+	"io"
+	"sync"
+
+	"go.uber.org/multierr"
+)
+
+// A WriteSyncer is an io.Writer that can also flush any buffered data. Note
+// that *os.File (and thus, os.Stderr and os.Stdout) implement WriteSyncer.
+type WriteSyncer interface {
+	io.Writer
+	Sync() error
+}
+
+// AddSync converts an io.Writer to a WriteSyncer. It attempts to be
+// intelligent: if the concrete type of the io.Writer implements WriteSyncer,
+// we'll use the existing Sync method. If it doesn't, we'll add a no-op Sync.
+func AddSync(w io.Writer) WriteSyncer {
+	switch w := w.(type) {
+	case WriteSyncer:
+		return w
+	default:
+		return writerWrapper{w}
+	}
+}
+
+type lockedWriteSyncer struct {
+	sync.Mutex
+	ws WriteSyncer
+}
+
+// Lock wraps a WriteSyncer in a mutex to make it safe for concurrent use. In
+// particular, *os.Files must be locked before use.
+func Lock(ws WriteSyncer) WriteSyncer {
+	if _, ok := ws.(*lockedWriteSyncer); ok {
+		// no need to layer on another lock
+		return ws
+	}
+	return &lockedWriteSyncer{ws: ws}
+}
+
+func (s *lockedWriteSyncer) Write(bs []byte) (int, error) {
+	s.Lock()
+	n, err := s.ws.Write(bs)
+	s.Unlock()
+	return n, err
+}
+
+func (s *lockedWriteSyncer) Sync() error {
+	s.Lock()
+	err := s.ws.Sync()
+	s.Unlock()
+	return err
+}
+
+type writerWrapper struct {
+	io.Writer
+}
+
+func (w writerWrapper) Sync() error {
+	return nil
+}
+
+type multiWriteSyncer []WriteSyncer
+
+// NewMultiWriteSyncer creates a WriteSyncer that duplicates its writes
+// and sync calls, much like io.MultiWriter.
+func NewMultiWriteSyncer(ws ...WriteSyncer) WriteSyncer {
+	if len(ws) == 1 {
+		return ws[0]
+	}
+	// Copy to protect against https://github.com/golang/go/issues/7809
+	return multiWriteSyncer(append([]WriteSyncer(nil), ws...))
+}
+
+// See https://golang.org/src/io/multi.go
+// When not all underlying syncers write the same number of bytes,
+// the smallest number is returned even though Write() is called on
+// all of them.
+func (ws multiWriteSyncer) Write(p []byte) (int, error) {
+	var writeErr error
+	nWritten := 0
+	for _, w := range ws {
+		n, err := w.Write(p)
+		writeErr = multierr.Append(writeErr, err)
+		if nWritten == 0 && n != 0 {
+			nWritten = n
+		} else if n < nWritten {
+			nWritten = n
+		}
+	}
+	return nWritten, writeErr
+}
+
+func (ws multiWriteSyncer) Sync() error {
+	var err error
+	for _, w := range ws {
+		err = multierr.Append(err, w.Sync())
+	}
+	return err
+}