use go1.11 with go mod

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

@@ -1,20 +0,0 @@
-// 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 Data struct {
-	ContentType string
-	Data        []byte
-}
-
-func (r Data) Render(w http.ResponseWriter) error {
-	if len(r.ContentType) > 0 {
-		w.Header()["Content-Type"] = []string{r.ContentType}
-	}
-	w.Write(r.Data)
-	return nil
-}