Splitted webpack config into base and dev. Re-use it in .storybook webpack config.

.storybook/webpack.config.js

@@ -1,34 +1 @@
-/* global module, __dirname, require */
-var webpack = require("webpack");
-const path = require("path");
-
-module.exports = {
-  module: {
-    loaders: [
-      {
-        test: /\.((png)|(eot)|(woff)|(woff2)|(ttf)|(svg)|(gif))(\?v=\d+\.\d+\.\d+)?$/,
-        loader: 'url-loader?limit=100000'
-      },
-      { test: /\.json$/, loader: 'json-loader' },
-      {
-        test: /\.css$/,
-        loader: 'style!css?modules&importLoaders=1!postcss'
-      },
-      {
-        loader: 'babel',
-        test: /\.js?$/,
-        exclude: /(node_modules|bower_components)/,
-        query: {
-          cacheDirectory: true,
-          presets: ['react', 'es2015'],
-          plugins: ['transform-class-properties', 'transform-object-assign', 'transform-object-rest-spread']
-        }
-      }
-    ]
-  },
-
-  postcss: [
-    require("postcss-import")({addDependencyTo: webpack}),
-    require("postcss-cssnext")()
-  ],
-};
+module.exports = require('../webpack.base.js');