clean webpack configuration code

config/webpack.common.js

@@ -8,11 +8,6 @@ const helpers = require('./helpers');
 const AssetsPlugin = require('assets-webpack-plugin');
 const CommonsChunkPlugin = require('webpack/lib/optimize/CommonsChunkPlugin');
 
-/*
- * Webpack Constants
- */
-const HMR = helpers.hasProcessFlag('hot');
-
 /*
  * Webpack configuration
  *
@@ -43,10 +38,6 @@ module.exports = function (options) {
             loader: 'babel-loader?cacheDirectory',
           }]
         },
-        {
-          test: /\.json$/,
-          use: 'json-loader',
-        },
         /*
          * File loader for supporting images, for example, in CSS files.
          */