diff --git a/vendor/github.com/grpc-ecosystem/grpc-gateway/runtime/marshal_jsonpb.go b/vendor/github.com/grpc-ecosystem/grpc-gateway/runtime/marshal_jsonpb.go
new file mode 100644
index 0000000..f0de351
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/grpc-gateway/runtime/marshal_jsonpb.go
@@ -0,0 +1,262 @@
+package runtime
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"reflect"
+
+	"github.com/golang/protobuf/jsonpb"
+	"github.com/golang/protobuf/proto"
+)
+
+// JSONPb is a Marshaler which marshals/unmarshals into/from JSON
+// with the "github.com/golang/protobuf/jsonpb".
+// It supports fully functionality of protobuf unlike JSONBuiltin.
+//
+// The NewDecoder method returns a DecoderWrapper, so the underlying
+// *json.Decoder methods can be used.
+type JSONPb jsonpb.Marshaler
+
+// ContentType always returns "application/json".
+func (*JSONPb) ContentType() string {
+	return "application/json"
+}
+
+// Marshal marshals "v" into JSON.
+func (j *JSONPb) Marshal(v interface{}) ([]byte, error) {
+	if _, ok := v.(proto.Message); !ok {
+		return j.marshalNonProtoField(v)
+	}
+
+	var buf bytes.Buffer
+	if err := j.marshalTo(&buf, v); err != nil {
+		return nil, err
+	}
+	return buf.Bytes(), nil
+}
+
+func (j *JSONPb) marshalTo(w io.Writer, v interface{}) error {
+	p, ok := v.(proto.Message)
+	if !ok {
+		buf, err := j.marshalNonProtoField(v)
+		if err != nil {
+			return err
+		}
+		_, err = w.Write(buf)
+		return err
+	}
+	return (*jsonpb.Marshaler)(j).Marshal(w, p)
+}
+
+var (
+	// protoMessageType is stored to prevent constant lookup of the same type at runtime.
+	protoMessageType = reflect.TypeOf((*proto.Message)(nil)).Elem()
+)
+
+// marshalNonProto marshals a non-message field of a protobuf message.
+// This function does not correctly marshals arbitrary data structure into JSON,
+// but it is only capable of marshaling non-message field values of protobuf,
+// i.e. primitive types, enums; pointers to primitives or enums; maps from
+// integer/string types to primitives/enums/pointers to messages.
+func (j *JSONPb) marshalNonProtoField(v interface{}) ([]byte, error) {
+	if v == nil {
+		return []byte("null"), nil
+	}
+	rv := reflect.ValueOf(v)
+	for rv.Kind() == reflect.Ptr {
+		if rv.IsNil() {
+			return []byte("null"), nil
+		}
+		rv = rv.Elem()
+	}
+
+	if rv.Kind() == reflect.Slice {
+		if rv.IsNil() {
+			if j.EmitDefaults {
+				return []byte("[]"), nil
+			}
+			return []byte("null"), nil
+		}
+
+		if rv.Type().Elem().Implements(protoMessageType) {
+			var buf bytes.Buffer
+			err := buf.WriteByte('[')
+			if err != nil {
+				return nil, err
+			}
+			for i := 0; i < rv.Len(); i++ {
+				if i != 0 {
+					err = buf.WriteByte(',')
+					if err != nil {
+						return nil, err
+					}
+				}
+				if err = (*jsonpb.Marshaler)(j).Marshal(&buf, rv.Index(i).Interface().(proto.Message)); err != nil {
+					return nil, err
+				}
+			}
+			err = buf.WriteByte(']')
+			if err != nil {
+				return nil, err
+			}
+
+			return buf.Bytes(), nil
+		}
+	}
+
+	if rv.Kind() == reflect.Map {
+		m := make(map[string]*json.RawMessage)
+		for _, k := range rv.MapKeys() {
+			buf, err := j.Marshal(rv.MapIndex(k).Interface())
+			if err != nil {
+				return nil, err
+			}
+			m[fmt.Sprintf("%v", k.Interface())] = (*json.RawMessage)(&buf)
+		}
+		if j.Indent != "" {
+			return json.MarshalIndent(m, "", j.Indent)
+		}
+		return json.Marshal(m)
+	}
+	if enum, ok := rv.Interface().(protoEnum); ok && !j.EnumsAsInts {
+		return json.Marshal(enum.String())
+	}
+	return json.Marshal(rv.Interface())
+}
+
+// Unmarshal unmarshals JSON "data" into "v"
+func (j *JSONPb) Unmarshal(data []byte, v interface{}) error {
+	return unmarshalJSONPb(data, v)
+}
+
+// NewDecoder returns a Decoder which reads JSON stream from "r".
+func (j *JSONPb) NewDecoder(r io.Reader) Decoder {
+	d := json.NewDecoder(r)
+	return DecoderWrapper{Decoder: d}
+}
+
+// DecoderWrapper is a wrapper around a *json.Decoder that adds
+// support for protos to the Decode method.
+type DecoderWrapper struct {
+	*json.Decoder
+}
+
+// Decode wraps the embedded decoder's Decode method to support
+// protos using a jsonpb.Unmarshaler.
+func (d DecoderWrapper) Decode(v interface{}) error {
+	return decodeJSONPb(d.Decoder, v)
+}
+
+// NewEncoder returns an Encoder which writes JSON stream into "w".
+func (j *JSONPb) NewEncoder(w io.Writer) Encoder {
+	return EncoderFunc(func(v interface{}) error {
+		if err := j.marshalTo(w, v); err != nil {
+			return err
+		}
+		// mimic json.Encoder by adding a newline (makes output
+		// easier to read when it contains multiple encoded items)
+		_, err := w.Write(j.Delimiter())
+		return err
+	})
+}
+
+func unmarshalJSONPb(data []byte, v interface{}) error {
+	d := json.NewDecoder(bytes.NewReader(data))
+	return decodeJSONPb(d, v)
+}
+
+func decodeJSONPb(d *json.Decoder, v interface{}) error {
+	p, ok := v.(proto.Message)
+	if !ok {
+		return decodeNonProtoField(d, v)
+	}
+	unmarshaler := &jsonpb.Unmarshaler{AllowUnknownFields: allowUnknownFields}
+	return unmarshaler.UnmarshalNext(d, p)
+}
+
+func decodeNonProtoField(d *json.Decoder, v interface{}) error {
+	rv := reflect.ValueOf(v)
+	if rv.Kind() != reflect.Ptr {
+		return fmt.Errorf("%T is not a pointer", v)
+	}
+	for rv.Kind() == reflect.Ptr {
+		if rv.IsNil() {
+			rv.Set(reflect.New(rv.Type().Elem()))
+		}
+		if rv.Type().ConvertibleTo(typeProtoMessage) {
+			unmarshaler := &jsonpb.Unmarshaler{AllowUnknownFields: allowUnknownFields}
+			return unmarshaler.UnmarshalNext(d, rv.Interface().(proto.Message))
+		}
+		rv = rv.Elem()
+	}
+	if rv.Kind() == reflect.Map {
+		if rv.IsNil() {
+			rv.Set(reflect.MakeMap(rv.Type()))
+		}
+		conv, ok := convFromType[rv.Type().Key().Kind()]
+		if !ok {
+			return fmt.Errorf("unsupported type of map field key: %v", rv.Type().Key())
+		}
+
+		m := make(map[string]*json.RawMessage)
+		if err := d.Decode(&m); err != nil {
+			return err
+		}
+		for k, v := range m {
+			result := conv.Call([]reflect.Value{reflect.ValueOf(k)})
+			if err := result[1].Interface(); err != nil {
+				return err.(error)
+			}
+			bk := result[0]
+			bv := reflect.New(rv.Type().Elem())
+			if err := unmarshalJSONPb([]byte(*v), bv.Interface()); err != nil {
+				return err
+			}
+			rv.SetMapIndex(bk, bv.Elem())
+		}
+		return nil
+	}
+	if _, ok := rv.Interface().(protoEnum); ok {
+		var repr interface{}
+		if err := d.Decode(&repr); err != nil {
+			return err
+		}
+		switch repr.(type) {
+		case string:
+			// TODO(yugui) Should use proto.StructProperties?
+			return fmt.Errorf("unmarshaling of symbolic enum %q not supported: %T", repr, rv.Interface())
+		case float64:
+			rv.Set(reflect.ValueOf(int32(repr.(float64))).Convert(rv.Type()))
+			return nil
+		default:
+			return fmt.Errorf("cannot assign %#v into Go type %T", repr, rv.Interface())
+		}
+	}
+	return d.Decode(v)
+}
+
+type protoEnum interface {
+	fmt.Stringer
+	EnumDescriptor() ([]byte, []int)
+}
+
+var typeProtoMessage = reflect.TypeOf((*proto.Message)(nil)).Elem()
+
+// Delimiter for newline encoded JSON streams.
+func (j *JSONPb) Delimiter() []byte {
+	return []byte("\n")
+}
+
+// allowUnknownFields helps not to return an error when the destination
+// is a struct and the input contains object keys which do not match any
+// non-ignored, exported fields in the destination.
+var allowUnknownFields = true
+
+// DisallowUnknownFields enables option in decoder (unmarshaller) to
+// return an error when it finds an unknown field. This function must be
+// called before using the JSON marshaller.
+func DisallowUnknownFields() {
+	allowUnknownFields = false
+}