diff --git a/vendor/go.uber.org/zap/zapcore/encoder.go b/vendor/go.uber.org/zap/zapcore/encoder.go
new file mode 100644
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+++ b/vendor/go.uber.org/zap/zapcore/encoder.go
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+// 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/json"
+	"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"
+
+// OmitKey defines the key to use when callers want to remove a key from log output.
+const OmitKey = ""
+
+// 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())
+}
+
+func encodeTimeLayout(t time.Time, layout string, enc PrimitiveArrayEncoder) {
+	type appendTimeEncoder interface {
+		AppendTimeLayout(time.Time, string)
+	}
+
+	if enc, ok := enc.(appendTimeEncoder); ok {
+		enc.AppendTimeLayout(t, layout)
+		return
+	}
+
+	enc.AppendString(t.Format(layout))
+}
+
+// ISO8601TimeEncoder serializes a time.Time to an ISO8601-formatted string
+// with millisecond precision.
+//
+// If enc supports AppendTimeLayout(t time.Time,layout string), it's used
+// instead of appending a pre-formatted string value.
+func ISO8601TimeEncoder(t time.Time, enc PrimitiveArrayEncoder) {
+	encodeTimeLayout(t, "2006-01-02T15:04:05.000Z0700", enc)
+}
+
+// RFC3339TimeEncoder serializes a time.Time to an RFC3339-formatted string.
+//
+// If enc supports AppendTimeLayout(t time.Time,layout string), it's used
+// instead of appending a pre-formatted string value.
+func RFC3339TimeEncoder(t time.Time, enc PrimitiveArrayEncoder) {
+	encodeTimeLayout(t, time.RFC3339, enc)
+}
+
+// RFC3339NanoTimeEncoder serializes a time.Time to an RFC3339-formatted string
+// with nanosecond precision.
+//
+// If enc supports AppendTimeLayout(t time.Time,layout string), it's used
+// instead of appending a pre-formatted string value.
+func RFC3339NanoTimeEncoder(t time.Time, enc PrimitiveArrayEncoder) {
+	encodeTimeLayout(t, time.RFC3339Nano, enc)
+}
+
+// TimeEncoderOfLayout returns TimeEncoder which serializes a time.Time using
+// given layout.
+func TimeEncoderOfLayout(layout string) TimeEncoder {
+	return func(t time.Time, enc PrimitiveArrayEncoder) {
+		encodeTimeLayout(t, layout, enc)
+	}
+}
+
+// UnmarshalText unmarshals text to a TimeEncoder.
+// "rfc3339nano" and "RFC3339Nano" are unmarshaled to RFC3339NanoTimeEncoder.
+// "rfc3339" and "RFC3339" are unmarshaled to RFC3339TimeEncoder.
+// "iso8601" and "ISO8601" are unmarshaled to ISO8601TimeEncoder.
+// "millis" is unmarshaled to EpochMillisTimeEncoder.
+// "nanos" is unmarshaled to EpochNanosEncoder.
+// Anything else is unmarshaled to EpochTimeEncoder.
+func (e *TimeEncoder) UnmarshalText(text []byte) error {
+	switch string(text) {
+	case "rfc3339nano", "RFC3339Nano":
+		*e = RFC3339NanoTimeEncoder
+	case "rfc3339", "RFC3339":
+		*e = RFC3339TimeEncoder
+	case "iso8601", "ISO8601":
+		*e = ISO8601TimeEncoder
+	case "millis":
+		*e = EpochMillisTimeEncoder
+	case "nanos":
+		*e = EpochNanosTimeEncoder
+	default:
+		*e = EpochTimeEncoder
+	}
+	return nil
+}
+
+// UnmarshalYAML unmarshals YAML to a TimeEncoder.
+// If value is an object with a "layout" field, it will be unmarshaled to  TimeEncoder with given layout.
+//     timeEncoder:
+//       layout: 06/01/02 03:04pm
+// If value is string, it uses UnmarshalText.
+//     timeEncoder: iso8601
+func (e *TimeEncoder) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var o struct {
+		Layout string `json:"layout" yaml:"layout"`
+	}
+	if err := unmarshal(&o); err == nil {
+		*e = TimeEncoderOfLayout(o.Layout)
+		return nil
+	}
+
+	var s string
+	if err := unmarshal(&s); err != nil {
+		return err
+	}
+	return e.UnmarshalText([]byte(s))
+}
+
+// UnmarshalJSON unmarshals JSON to a TimeEncoder as same way UnmarshalYAML does.
+func (e *TimeEncoder) UnmarshalJSON(data []byte) error {
+	return e.UnmarshalYAML(func(v interface{}) error {
+		return json.Unmarshal(data, v)
+	})
+}
+
+// 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))
+}
+
+// MillisDurationEncoder serializes a time.Duration to an integer number of
+// milliseconds elapsed.
+func MillisDurationEncoder(d time.Duration, enc PrimitiveArrayEncoder) {
+	enc.AppendInt64(d.Nanoseconds() / 1e6)
+}
+
+// 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
+	case "ms":
+		*e = MillisDurationEncoder
+	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"`
+	FunctionKey   string `json:"functionKey" yaml:"functionKey"`
+	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"`
+	// Configures the field separator used by the console encoder. Defaults
+	// to tab.
+	ConsoleSeparator string `json:"consoleSeparator" yaml:"consoleSeparator"`
+}
+
+// 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 can be
+	// 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. Any fields that are empty,
+	// including fields on the `Entry` type, should be omitted.
+	EncodeEntry(Entry, []Field) (*buffer.Buffer, error)
+}