add dev mode, update readme

build/webpack.dev.conf.js

@@ -0,0 +1,28 @@
+var webpack = require('webpack')
+var merge = require('webpack-merge')
+var HtmlWebpackPlugin = require('html-webpack-plugin')
+var baseConfig = require('./webpack.base.conf')
+var path = require('path')
+
+var projectRoot = path.resolve(__dirname, '../')
+
+module.exports = merge(baseConfig, {
+  entry: './dev/index.js',
+  devServer: {
+    historyApiFallback: true,
+    noInfo: true,
+    overlay: true,
+    open: true,
+    hot: true,
+    inline: true
+  },
+  devtool: '#eval-source-map',
+  plugins: [
+    new HtmlWebpackPlugin({
+      template: './dev/index.html',
+      filename: 'index.html',
+      inject: true
+    }),
+    new webpack.HotModuleReplacementPlugin()
+  ]
+})