fix(es6): support node.js 4

lib/webpack.config.base.js

@@ -143,15 +143,14 @@ module.exports = function (type, options) {
 			}
 		)
 		// add plugins
-		config.plugins = [
-			...config.plugins,
+		config.plugins = config.plugins.concat([
 			new webpack.HotModuleReplacementPlugin(),
 			new webpack.NoErrorsPlugin(),
 			new webpack.DefinePlugin({
 				'__DEV__': true,
 				'process.env': JSON.stringify('development')
 			})
-		]
+		])
 		// inject autoInstall
 		if (options.autoInstall) {
 			config.plugins.push(new NpmInstallPlugin())
@@ -178,8 +177,7 @@ module.exports = function (type, options) {
 				loader: ExtractTextPlugin.extract('style-loader', 'css-loader!postcss-loader')
 			}
 		)
-		config.plugins = [
-			...config.plugins,
+		config.plugins = config.plugins.concat([
 			new webpack.optimize.OccurenceOrderPlugin(),
 			/*eslint-disable */
 			new webpack.DefinePlugin({
@@ -196,7 +194,7 @@ module.exports = function (type, options) {
 				comments: false
 			}),
 			new ExtractTextPlugin('styles.[contenthash].css')
-		]
+		])
 	}
 	return config
 }

package.json

@@ -96,5 +96,8 @@
       "example/**",
       "build/**"
     ]
+  },
+  "testen": {
+    "node": ["4.0.0", "4.2.4", "5.6.0"]
   }
 }

readme.md

@@ -35,7 +35,7 @@ Real world example, run `npm start` in [this repo](https://github.com/egoist/how
 
 ## Usage
 
-Installing `tooling` via NPM is easy (**WARN: only support node >=5**):
+Installing `tooling` via NPM is easy (**WARN: only work for Node.js >= 4**):
 
 ```bash
 npm install tooling -g