add functions/vendor files

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

@@ -0,0 +1,31 @@
+// 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 render
+
+import "net/http"
+
+type Render interface {
+	Render(http.ResponseWriter) error
+}
+
+var (
+	_ Render     = JSON{}
+	_ Render     = IndentedJSON{}
+	_ Render     = XML{}
+	_ Render     = String{}
+	_ Render     = Redirect{}
+	_ Render     = Data{}
+	_ Render     = HTML{}
+	_ HTMLRender = HTMLDebug{}
+	_ HTMLRender = HTMLProduction{}
+	_ Render     = YAML{}
+)
+
+func writeContentType(w http.ResponseWriter, value []string) {
+	header := w.Header()
+	if val := header["Content-Type"]; len(val) == 0 {
+		header["Content-Type"] = value
+	}
+}