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

webpack.dev.js

@@ -0,0 +1,37 @@
+/* global module, __dirname, require */
+const path = require('path');
+const webpack = require('webpack');
+const merge = require('webpack-merge');
+const HOST = 'localhost';
+const PORT = '8080';
+
+module.exports = merge.smart(require('./webpack.base.js'), {
+  entry: {
+    cms: [
+      'webpack/hot/dev-server',
+      `webpack-dev-server/client?http://${HOST}:${PORT}/`,
+      'react-hot-loader/patch',
+      './index'
+    ],
+  },
+  output: {
+    path: path.join(__dirname, 'dist'),
+    filename: '[name].js',
+    publicPath: `http://${HOST}:${PORT}/`,
+  },
+  context: path.join(__dirname, 'src'),
+  plugins: [
+    new webpack.optimize.OccurenceOrderPlugin(),
+    new webpack.HotModuleReplacementPlugin(),
+    new webpack.NoErrorsPlugin(),
+    new webpack.ProvidePlugin({
+      'fetch': 'imports?this=>global!exports?global.fetch!whatwg-fetch'
+    })
+  ],
+  devServer: {
+    hot: true,
+    contentBase: 'example/',
+    historyApiFallback: true,
+    devTool: 'cheap-module-source-map'
+  },
+});