FIX: can't resolve json files in require call

Author: zzhjerry

template/build/webpack.base.conf.js

@@ -20,7 +20,7 @@ module.exports = {
     filename: '[name].js'
   },
   resolve: {
-    extensions: ['', '.js', '.vue'],
+    extensions: ['', '.js', '.json', '.vue'],
     fallback: [path.join(__dirname, '../node_modules')],
     alias: {
       {{#if_eq build "standalone"}}