use go1.11 with go mod

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

@@ -1,41 +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 (
-	"encoding/json"
-	"net/http"
-)
-
-type (
-	JSON struct {
-		Data interface{}
-	}
-
-	IndentedJSON struct {
-		Data interface{}
-	}
-)
-
-var jsonContentType = []string{"application/json; charset=utf-8"}
-
-func (r JSON) Render(w http.ResponseWriter) error {
-	return WriteJSON(w, r.Data)
-}
-
-func (r IndentedJSON) Render(w http.ResponseWriter) error {
-	writeContentType(w, jsonContentType)
-	jsonBytes, err := json.MarshalIndent(r.Data, "", "    ")
-	if err != nil {
-		return err
-	}
-	w.Write(jsonBytes)
-	return nil
-}
-
-func WriteJSON(w http.ResponseWriter, obj interface{}) error {
-	writeContentType(w, jsonContentType)
-	return json.NewEncoder(w).Encode(obj)
-}