Upgrade gin-gonic to latest master, fix compatibility issues

vendor/github.com/gin-gonic/gin/render/msgpack.go

@@ -0,0 +1,31 @@
+// Copyright 2017 Manu Martinez-Almeida.  All rights reserved.
+// Use of this source code is governed by a MIT style
+// license that can be found in the LICENSE file.
+
+package render
+
+import (
+	"net/http"
+
+	"github.com/ugorji/go/codec"
+)
+
+type MsgPack struct {
+	Data interface{}
+}
+
+var msgpackContentType = []string{"application/msgpack; charset=utf-8"}
+
+func (r MsgPack) WriteContentType(w http.ResponseWriter) {
+	writeContentType(w, msgpackContentType)
+}
+
+func (r MsgPack) Render(w http.ResponseWriter) error {
+	return WriteMsgPack(w, r.Data)
+}
+
+func WriteMsgPack(w http.ResponseWriter, obj interface{}) error {
+	writeContentType(w, msgpackContentType)
+	var h codec.Handle = new(codec.MsgpackHandle)
+	return codec.NewEncoder(w, h).Encode(obj)
+}