add functions/vendor files

vendor/github.com/gin-gonic/gin/binding/json.go

@@ -0,0 +1,25 @@
+// Copyright 2014 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 binding
+
+import (
+	"encoding/json"
+
+	"net/http"
+)
+
+type jsonBinding struct{}
+
+func (jsonBinding) Name() string {
+	return "json"
+}
+
+func (jsonBinding) Bind(req *http.Request, obj interface{}) error {
+	decoder := json.NewDecoder(req.Body)
+	if err := decoder.Decode(obj); err != nil {
+		return err
+	}
+	return validate(obj)
+}