diff --git a/vendor/github.com/go-errors/errors/.travis.yml b/vendor/github.com/go-errors/errors/.travis.yml
new file mode 100644
index 0000000..9d00fdd
--- /dev/null
+++ b/vendor/github.com/go-errors/errors/.travis.yml
@@ -0,0 +1,5 @@
+language: go
+
+go:
+  - "1.8.x"
+  - "1.10.x"
diff --git a/vendor/github.com/go-errors/errors/LICENSE.MIT b/vendor/github.com/go-errors/errors/LICENSE.MIT
new file mode 100644
index 0000000..c9a5b2e
--- /dev/null
+++ b/vendor/github.com/go-errors/errors/LICENSE.MIT
@@ -0,0 +1,7 @@
+Copyright (c) 2015 Conrad Irwin <conrad@bugsnag.com>
+
+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/github.com/go-errors/errors/README.md b/vendor/github.com/go-errors/errors/README.md
new file mode 100644
index 0000000..5d4f187
--- /dev/null
+++ b/vendor/github.com/go-errors/errors/README.md
@@ -0,0 +1,66 @@
+go-errors/errors
+================
+
+[![Build Status](https://travis-ci.org/go-errors/errors.svg?branch=master)](https://travis-ci.org/go-errors/errors)
+
+Package errors adds stacktrace support to errors in go.
+
+This is particularly useful when you want to understand the state of execution
+when an error was returned unexpectedly.
+
+It provides the type \*Error which implements the standard golang error
+interface, so you can use this library interchangably with code that is
+expecting a normal error return.
+
+Usage
+-----
+
+Full documentation is available on
+[godoc](https://godoc.org/github.com/go-errors/errors), but here's a simple
+example:
+
+```go
+package crashy
+
+import "github.com/go-errors/errors"
+
+var Crashed = errors.Errorf("oh dear")
+
+func Crash() error {
+    return errors.New(Crashed)
+}
+```
+
+This can be called as follows:
+
+```go
+package main
+
+import (
+    "crashy"
+    "fmt"
+    "github.com/go-errors/errors"
+)
+
+func main() {
+    err := crashy.Crash()
+    if err != nil {
+        if errors.Is(err, crashy.Crashed) {
+            fmt.Println(err.(*errors.Error).ErrorStack())
+        } else {
+            panic(err)
+        }
+    }
+}
+```
+
+Meta-fu
+-------
+
+This package was original written to allow reporting to
+[Bugsnag](https://bugsnag.com/) from
+[bugsnag-go](https://github.com/bugsnag/bugsnag-go), but after I found similar
+packages by Facebook and Dropbox, it was moved to one canonical location so
+everyone can benefit.
+
+This package is licensed under the MIT license, see LICENSE.MIT for details.
diff --git a/vendor/github.com/go-errors/errors/cover.out b/vendor/github.com/go-errors/errors/cover.out
new file mode 100644
index 0000000..ab18b05
--- /dev/null
+++ b/vendor/github.com/go-errors/errors/cover.out
@@ -0,0 +1,89 @@
+mode: set
+github.com/go-errors/errors/stackframe.go:27.51,30.25 2 1
+github.com/go-errors/errors/stackframe.go:33.2,38.8 3 1
+github.com/go-errors/errors/stackframe.go:30.25,32.3 1 0
+github.com/go-errors/errors/stackframe.go:43.47,44.31 1 1
+github.com/go-errors/errors/stackframe.go:47.2,47.48 1 1
+github.com/go-errors/errors/stackframe.go:44.31,46.3 1 1
+github.com/go-errors/errors/stackframe.go:52.42,56.16 3 1
+github.com/go-errors/errors/stackframe.go:60.2,60.60 1 1
+github.com/go-errors/errors/stackframe.go:56.16,58.3 1 0
+github.com/go-errors/errors/stackframe.go:64.55,67.16 2 1
+github.com/go-errors/errors/stackframe.go:71.2,72.61 2 1
+github.com/go-errors/errors/stackframe.go:76.2,76.66 1 1
+github.com/go-errors/errors/stackframe.go:67.16,69.3 1 0
+github.com/go-errors/errors/stackframe.go:72.61,74.3 1 0
+github.com/go-errors/errors/stackframe.go:79.56,91.63 3 1
+github.com/go-errors/errors/stackframe.go:95.2,95.53 1 1
+github.com/go-errors/errors/stackframe.go:100.2,101.18 2 1
+github.com/go-errors/errors/stackframe.go:91.63,94.3 2 1
+github.com/go-errors/errors/stackframe.go:95.53,98.3 2 1
+github.com/go-errors/errors/error.go:70.32,73.23 2 1
+github.com/go-errors/errors/error.go:80.2,85.3 3 1
+github.com/go-errors/errors/error.go:74.2,75.10 1 1
+github.com/go-errors/errors/error.go:76.2,77.28 1 1
+github.com/go-errors/errors/error.go:92.43,95.23 2 1
+github.com/go-errors/errors/error.go:104.2,109.3 3 1
+github.com/go-errors/errors/error.go:96.2,97.11 1 1
+github.com/go-errors/errors/error.go:98.2,99.10 1 1
+github.com/go-errors/errors/error.go:100.2,101.28 1 1
+github.com/go-errors/errors/error.go:115.39,117.19 1 1
+github.com/go-errors/errors/error.go:121.2,121.29 1 1
+github.com/go-errors/errors/error.go:125.2,125.43 1 1
+github.com/go-errors/errors/error.go:129.2,129.14 1 1
+github.com/go-errors/errors/error.go:117.19,119.3 1 1
+github.com/go-errors/errors/error.go:121.29,123.3 1 1
+github.com/go-errors/errors/error.go:125.43,127.3 1 1
+github.com/go-errors/errors/error.go:135.53,137.2 1 1
+github.com/go-errors/errors/error.go:140.34,142.2 1 1
+github.com/go-errors/errors/error.go:146.34,149.42 2 1
+github.com/go-errors/errors/error.go:153.2,153.20 1 1
+github.com/go-errors/errors/error.go:149.42,151.3 1 1
+github.com/go-errors/errors/error.go:158.39,160.2 1 1
+github.com/go-errors/errors/error.go:164.46,165.23 1 1
+github.com/go-errors/errors/error.go:173.2,173.19 1 1
+github.com/go-errors/errors/error.go:165.23,168.32 2 1
+github.com/go-errors/errors/error.go:168.32,170.4 1 1
+github.com/go-errors/errors/error.go:177.37,178.42 1 1
+github.com/go-errors/errors/error.go:181.2,181.41 1 1
+github.com/go-errors/errors/error.go:178.42,180.3 1 1
+github.com/go-errors/errors/parse_panic.go:10.39,12.2 1 1
+github.com/go-errors/errors/parse_panic.go:16.46,24.34 5 1
+github.com/go-errors/errors/parse_panic.go:70.2,70.43 1 1
+github.com/go-errors/errors/parse_panic.go:73.2,73.55 1 0
+github.com/go-errors/errors/parse_panic.go:24.34,27.23 2 1
+github.com/go-errors/errors/parse_panic.go:27.23,28.42 1 1
+github.com/go-errors/errors/parse_panic.go:28.42,31.5 2 1
+github.com/go-errors/errors/parse_panic.go:31.6,33.5 1 0
+github.com/go-errors/errors/parse_panic.go:35.5,35.29 1 1
+github.com/go-errors/errors/parse_panic.go:35.29,36.86 1 1
+github.com/go-errors/errors/parse_panic.go:36.86,38.5 1 1
+github.com/go-errors/errors/parse_panic.go:40.5,40.32 1 1
+github.com/go-errors/errors/parse_panic.go:40.32,41.18 1 1
+github.com/go-errors/errors/parse_panic.go:45.4,46.46 2 1
+github.com/go-errors/errors/parse_panic.go:51.4,53.23 2 1
+github.com/go-errors/errors/parse_panic.go:57.4,58.18 2 1
+github.com/go-errors/errors/parse_panic.go:62.4,63.17 2 1
+github.com/go-errors/errors/parse_panic.go:41.18,43.10 2 1
+github.com/go-errors/errors/parse_panic.go:46.46,49.5 2 1
+github.com/go-errors/errors/parse_panic.go:53.23,55.5 1 0
+github.com/go-errors/errors/parse_panic.go:58.18,60.5 1 0
+github.com/go-errors/errors/parse_panic.go:63.17,65.10 2 1
+github.com/go-errors/errors/parse_panic.go:70.43,72.3 1 1
+github.com/go-errors/errors/parse_panic.go:80.85,82.29 2 1
+github.com/go-errors/errors/parse_panic.go:85.2,85.15 1 1
+github.com/go-errors/errors/parse_panic.go:88.2,90.63 2 1
+github.com/go-errors/errors/parse_panic.go:94.2,94.53 1 1
+github.com/go-errors/errors/parse_panic.go:99.2,101.36 2 1
+github.com/go-errors/errors/parse_panic.go:105.2,106.15 2 1
+github.com/go-errors/errors/parse_panic.go:109.2,112.49 3 1
+github.com/go-errors/errors/parse_panic.go:116.2,117.16 2 1
+github.com/go-errors/errors/parse_panic.go:121.2,126.8 1 1
+github.com/go-errors/errors/parse_panic.go:82.29,84.3 1 0
+github.com/go-errors/errors/parse_panic.go:85.15,87.3 1 1
+github.com/go-errors/errors/parse_panic.go:90.63,93.3 2 1
+github.com/go-errors/errors/parse_panic.go:94.53,97.3 2 1
+github.com/go-errors/errors/parse_panic.go:101.36,103.3 1 0
+github.com/go-errors/errors/parse_panic.go:106.15,108.3 1 0
+github.com/go-errors/errors/parse_panic.go:112.49,114.3 1 1
+github.com/go-errors/errors/parse_panic.go:117.16,119.3 1 0
diff --git a/vendor/github.com/go-errors/errors/error.go b/vendor/github.com/go-errors/errors/error.go
new file mode 100644
index 0000000..60062a4
--- /dev/null
+++ b/vendor/github.com/go-errors/errors/error.go
@@ -0,0 +1,217 @@
+// Package errors provides errors that have stack-traces.
+//
+// This is particularly useful when you want to understand the
+// state of execution when an error was returned unexpectedly.
+//
+// It provides the type *Error which implements the standard
+// golang error interface, so you can use this library interchangably
+// with code that is expecting a normal error return.
+//
+// For example:
+//
+//  package crashy
+//
+//  import "github.com/go-errors/errors"
+//
+//  var Crashed = errors.Errorf("oh dear")
+//
+//  func Crash() error {
+//      return errors.New(Crashed)
+//  }
+//
+// This can be called as follows:
+//
+//  package main
+//
+//  import (
+//      "crashy"
+//      "fmt"
+//      "github.com/go-errors/errors"
+//  )
+//
+//  func main() {
+//      err := crashy.Crash()
+//      if err != nil {
+//          if errors.Is(err, crashy.Crashed) {
+//              fmt.Println(err.(*errors.Error).ErrorStack())
+//          } else {
+//              panic(err)
+//          }
+//      }
+//  }
+//
+// This package was original written to allow reporting to Bugsnag,
+// but after I found similar packages by Facebook and Dropbox, it
+// was moved to one canonical location so everyone can benefit.
+package errors
+
+import (
+	"bytes"
+	"fmt"
+	"reflect"
+	"runtime"
+)
+
+// The maximum number of stackframes on any error.
+var MaxStackDepth = 50
+
+// Error is an error with an attached stacktrace. It can be used
+// wherever the builtin error interface is expected.
+type Error struct {
+	Err    error
+	stack  []uintptr
+	frames []StackFrame
+	prefix string
+}
+
+// New makes an Error from the given value. If that value is already an
+// error then it will be used directly, if not, it will be passed to
+// fmt.Errorf("%v"). The stacktrace will point to the line of code that
+// called New.
+func New(e interface{}) *Error {
+	var err error
+
+	switch e := e.(type) {
+	case error:
+		err = e
+	default:
+		err = fmt.Errorf("%v", e)
+	}
+
+	stack := make([]uintptr, MaxStackDepth)
+	length := runtime.Callers(2, stack[:])
+	return &Error{
+		Err:   err,
+		stack: stack[:length],
+	}
+}
+
+// Wrap makes an Error from the given value. If that value is already an
+// error then it will be used directly, if not, it will be passed to
+// fmt.Errorf("%v"). The skip parameter indicates how far up the stack
+// to start the stacktrace. 0 is from the current call, 1 from its caller, etc.
+func Wrap(e interface{}, skip int) *Error {
+	var err error
+
+	switch e := e.(type) {
+	case *Error:
+		return e
+	case error:
+		err = e
+	default:
+		err = fmt.Errorf("%v", e)
+	}
+
+	stack := make([]uintptr, MaxStackDepth)
+	length := runtime.Callers(2+skip, stack[:])
+	return &Error{
+		Err:   err,
+		stack: stack[:length],
+	}
+}
+
+// WrapPrefix makes an Error from the given value. If that value is already an
+// error then it will be used directly, if not, it will be passed to
+// fmt.Errorf("%v"). The prefix parameter is used to add a prefix to the
+// error message when calling Error(). The skip parameter indicates how far
+// up the stack to start the stacktrace. 0 is from the current call,
+// 1 from its caller, etc.
+func WrapPrefix(e interface{}, prefix string, skip int) *Error {
+
+	err := Wrap(e, 1+skip)
+
+	if err.prefix != "" {
+		prefix = fmt.Sprintf("%s: %s", prefix, err.prefix)
+	}
+
+	return &Error{
+		Err:    err.Err,
+		stack:  err.stack,
+		prefix: prefix,
+	}
+
+}
+
+// Is detects whether the error is equal to a given error. Errors
+// are considered equal by this function if they are the same object,
+// or if they both contain the same error inside an errors.Error.
+func Is(e error, original error) bool {
+
+	if e == original {
+		return true
+	}
+
+	if e, ok := e.(*Error); ok {
+		return Is(e.Err, original)
+	}
+
+	if original, ok := original.(*Error); ok {
+		return Is(e, original.Err)
+	}
+
+	return false
+}
+
+// Errorf creates a new error with the given message. You can use it
+// as a drop-in replacement for fmt.Errorf() to provide descriptive
+// errors in return values.
+func Errorf(format string, a ...interface{}) *Error {
+	return Wrap(fmt.Errorf(format, a...), 1)
+}
+
+// Error returns the underlying error's message.
+func (err *Error) Error() string {
+
+	msg := err.Err.Error()
+	if err.prefix != "" {
+		msg = fmt.Sprintf("%s: %s", err.prefix, msg)
+	}
+
+	return msg
+}
+
+// Stack returns the callstack formatted the same way that go does
+// in runtime/debug.Stack()
+func (err *Error) Stack() []byte {
+	buf := bytes.Buffer{}
+
+	for _, frame := range err.StackFrames() {
+		buf.WriteString(frame.String())
+	}
+
+	return buf.Bytes()
+}
+
+// Callers satisfies the bugsnag ErrorWithCallerS() interface
+// so that the stack can be read out.
+func (err *Error) Callers() []uintptr {
+	return err.stack
+}
+
+// ErrorStack returns a string that contains both the
+// error message and the callstack.
+func (err *Error) ErrorStack() string {
+	return err.TypeName() + " " + err.Error() + "\n" + string(err.Stack())
+}
+
+// StackFrames returns an array of frames containing information about the
+// stack.
+func (err *Error) StackFrames() []StackFrame {
+	if err.frames == nil {
+		err.frames = make([]StackFrame, len(err.stack))
+
+		for i, pc := range err.stack {
+			err.frames[i] = NewStackFrame(pc)
+		}
+	}
+
+	return err.frames
+}
+
+// TypeName returns the type this error. e.g. *errors.stringError.
+func (err *Error) TypeName() string {
+	if _, ok := err.Err.(uncaughtPanic); ok {
+		return "panic"
+	}
+	return reflect.TypeOf(err.Err).String()
+}
diff --git a/vendor/github.com/go-errors/errors/parse_panic.go b/vendor/github.com/go-errors/errors/parse_panic.go
new file mode 100644
index 0000000..cc37052
--- /dev/null
+++ b/vendor/github.com/go-errors/errors/parse_panic.go
@@ -0,0 +1,127 @@
+package errors
+
+import (
+	"strconv"
+	"strings"
+)
+
+type uncaughtPanic struct{ message string }
+
+func (p uncaughtPanic) Error() string {
+	return p.message
+}
+
+// ParsePanic allows you to get an error object from the output of a go program
+// that panicked. This is particularly useful with https://github.com/mitchellh/panicwrap.
+func ParsePanic(text string) (*Error, error) {
+	lines := strings.Split(text, "\n")
+
+	state := "start"
+
+	var message string
+	var stack []StackFrame
+
+	for i := 0; i < len(lines); i++ {
+		line := lines[i]
+
+		if state == "start" {
+			if strings.HasPrefix(line, "panic: ") {
+				message = strings.TrimPrefix(line, "panic: ")
+				state = "seek"
+			} else {
+				return nil, Errorf("bugsnag.panicParser: Invalid line (no prefix): %s", line)
+			}
+
+		} else if state == "seek" {
+			if strings.HasPrefix(line, "goroutine ") && strings.HasSuffix(line, "[running]:") {
+				state = "parsing"
+			}
+
+		} else if state == "parsing" {
+			if line == "" {
+				state = "done"
+				break
+			}
+			createdBy := false
+			if strings.HasPrefix(line, "created by ") {
+				line = strings.TrimPrefix(line, "created by ")
+				createdBy = true
+			}
+
+			i++
+
+			if i >= len(lines) {
+				return nil, Errorf("bugsnag.panicParser: Invalid line (unpaired): %s", line)
+			}
+
+			frame, err := parsePanicFrame(line, lines[i], createdBy)
+			if err != nil {
+				return nil, err
+			}
+
+			stack = append(stack, *frame)
+			if createdBy {
+				state = "done"
+				break
+			}
+		}
+	}
+
+	if state == "done" || state == "parsing" {
+		return &Error{Err: uncaughtPanic{message}, frames: stack}, nil
+	}
+	return nil, Errorf("could not parse panic: %v", text)
+}
+
+// The lines we're passing look like this:
+//
+//     main.(*foo).destruct(0xc208067e98)
+//             /0/go/src/github.com/bugsnag/bugsnag-go/pan/main.go:22 +0x151
+func parsePanicFrame(name string, line string, createdBy bool) (*StackFrame, error) {
+	idx := strings.LastIndex(name, "(")
+	if idx == -1 && !createdBy {
+		return nil, Errorf("bugsnag.panicParser: Invalid line (no call): %s", name)
+	}
+	if idx != -1 {
+		name = name[:idx]
+	}
+	pkg := ""
+
+	if lastslash := strings.LastIndex(name, "/"); lastslash >= 0 {
+		pkg += name[:lastslash] + "/"
+		name = name[lastslash+1:]
+	}
+	if period := strings.Index(name, "."); period >= 0 {
+		pkg += name[:period]
+		name = name[period+1:]
+	}
+
+	name = strings.Replace(name, "·", ".", -1)
+
+	if !strings.HasPrefix(line, "\t") {
+		return nil, Errorf("bugsnag.panicParser: Invalid line (no tab): %s", line)
+	}
+
+	idx = strings.LastIndex(line, ":")
+	if idx == -1 {
+		return nil, Errorf("bugsnag.panicParser: Invalid line (no line number): %s", line)
+	}
+	file := line[1:idx]
+
+	number := line[idx+1:]
+	if idx = strings.Index(number, " +"); idx > -1 {
+		number = number[:idx]
+	}
+
+	lno, err := strconv.ParseInt(number, 10, 32)
+	if err != nil {
+		return nil, Errorf("bugsnag.panicParser: Invalid line (bad line number): %s", line)
+	}
+
+	return &StackFrame{
+		File:       file,
+		LineNumber: int(lno),
+		Package:    pkg,
+		Name:       name,
+	}, nil
+}
diff --git a/vendor/github.com/go-errors/errors/stackframe.go b/vendor/github.com/go-errors/errors/stackframe.go
new file mode 100644
index 0000000..750ab9a
--- /dev/null
+++ b/vendor/github.com/go-errors/errors/stackframe.go
@@ -0,0 +1,102 @@
+package errors
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"runtime"
+	"strings"
+)
+
+// A StackFrame contains all necessary information about to generate a line
+// in a callstack.
+type StackFrame struct {
+	// The path to the file containing this ProgramCounter
+	File string
+	// The LineNumber in that file
+	LineNumber int
+	// The Name of the function that contains this ProgramCounter
+	Name string
+	// The Package that contains this function
+	Package string
+	// The underlying ProgramCounter
+	ProgramCounter uintptr
+}
+
+// NewStackFrame popoulates a stack frame object from the program counter.
+func NewStackFrame(pc uintptr) (frame StackFrame) {
+
+	frame = StackFrame{ProgramCounter: pc}
+	if frame.Func() == nil {
+		return
+	}
+	frame.Package, frame.Name = packageAndName(frame.Func())
+
+	// pc -1 because the program counters we use are usually return addresses,
+	// and we want to show the line that corresponds to the function call
+	frame.File, frame.LineNumber = frame.Func().FileLine(pc - 1)
+	return
+
+}
+
+// Func returns the function that contained this frame.
+func (frame *StackFrame) Func() *runtime.Func {
+	if frame.ProgramCounter == 0 {
+		return nil
+	}
+	return runtime.FuncForPC(frame.ProgramCounter)
+}
+
+// String returns the stackframe formatted in the same way as go does
+// in runtime/debug.Stack()
+func (frame *StackFrame) String() string {
+	str := fmt.Sprintf("%s:%d (0x%x)\n", frame.File, frame.LineNumber, frame.ProgramCounter)
+
+	source, err := frame.SourceLine()
+	if err != nil {
+		return str
+	}
+
+	return str + fmt.Sprintf("\t%s: %s\n", frame.Name, source)
+}
+
+// SourceLine gets the line of code (from File and Line) of the original source if possible.
+func (frame *StackFrame) SourceLine() (string, error) {
+	data, err := ioutil.ReadFile(frame.File)
+
+	if err != nil {
+		return "", New(err)
+	}
+
+	lines := bytes.Split(data, []byte{'\n'})
+	if frame.LineNumber <= 0 || frame.LineNumber >= len(lines) {
+		return "???", nil
+	}
+	// -1 because line-numbers are 1 based, but our array is 0 based
+	return string(bytes.Trim(lines[frame.LineNumber-1], " \t")), nil
+}
+
+func packageAndName(fn *runtime.Func) (string, string) {
+	name := fn.Name()
+	pkg := ""
+
+	// The name includes the path name to the package, which is unnecessary
+	// since the file name is already included.  Plus, it has center dots.
+	// That is, we see
+	//  runtime/debug.*T·ptrmethod
+	// and want
+	//  *T.ptrmethod
+	// Since the package path might contains dots (e.g. code.google.com/...),
+	// we first remove the path prefix if there is one.
+	if lastslash := strings.LastIndex(name, "/"); lastslash >= 0 {
+		pkg += name[:lastslash] + "/"
+		name = name[lastslash+1:]
+	}
+	if period := strings.Index(name, "."); period >= 0 {
+		pkg += name[:period]
+		name = name[period+1:]
+	}
+
+	name = strings.Replace(name, "·", ".", -1)
+	return pkg, name
+}