Fixed Content-Type for json render. Thank you @mdigger

render/render.go

@@ -42,7 +42,7 @@ func writeHeader(w http.ResponseWriter, code int, contentType string) {
 }
 
 func (_ jsonRender) Render(w http.ResponseWriter, code int, data ...interface{}) error {
-	writeHeader(w, code, "application/xml")
+	writeHeader(w, code, "application/json")
 	encoder := json.NewEncoder(w)
 	return encoder.Encode(data[0])
 }