add emitFile in url-loader options (#576)

Author: dunhuang

packages/razzle/config/createConfig.js

@@ -168,6 +168,7 @@ module.exports = (
           options: {
             limit: 10000,
             name: 'static/media/[name].[hash:8].[ext]',
+            emitFile: IS_NODE ? false : true
           },
         },