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..95bdb0a
--- /dev/null
+++ b/vendor/go.uber.org/zap/zapcore/field.go
@@ -0,0 +1,233 @@
+// 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 that is
+	// representable by a UnixNano() stored as an int64.
+	TimeType
+	// TimeFullType indicates that the field carries a time.Time stored as-is.
+	TimeFullType
+	// 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
+
+	// InlineMarshalerType indicates that the field carries an ObjectMarshaler
+	// that should be inlined.
+	InlineMarshalerType
+)
+
+// 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 InlineMarshalerType:
+		err = f.Interface.(ObjectMarshaler).MarshalLogObject(enc)
+	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 TimeFullType:
+		enc.AddTime(f.Key, f.Interface.(time.Time))
+	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:
+		err = encodeStringer(f.Key, f.Interface, enc)
+	case ErrorType:
+		err = 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)
+	}
+}
+
+func encodeStringer(key string, stringer interface{}, enc ObjectEncoder) (retErr error) {
+	// Try to capture panics (from nil references or otherwise) when calling
+	// the String() method, similar to https://golang.org/src/fmt/print.go#L540
+	defer func() {
+		if err := recover(); err != nil {
+			// If it's a nil pointer, just say "<nil>". The likeliest causes are a
+			// Stringer that fails to guard against nil or a nil pointer for a
+			// value receiver, and in either case, "<nil>" is a nice result.
+			if v := reflect.ValueOf(stringer); v.Kind() == reflect.Ptr && v.IsNil() {
+				enc.AddString(key, "<nil>")
+				return
+			}
+
+			retErr = fmt.Errorf("PANIC=%v", err)
+		}
+	}()
+
+	enc.AddString(key, stringer.(fmt.Stringer).String())
+	return nil
+}