Add build tag nomsgpack (#1852)

* add build tag nomsgpack

* Update copyright

* Update copyright

render/msgpack.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a MIT style
 // license that can be found in the LICENSE file.
 
+// +build !nomsgpack
+
 package render
 
 import (
@@ -10,6 +12,10 @@ import (
 	"github.com/ugorji/go/codec"
 )
 
+var (
+	_ Render = MsgPack{}
+)
+
 // MsgPack contains the given interface object.
 type MsgPack struct {
 	Data interface{}