add test and update webpack config

[new] add test config
[new] add breadcrumb test
[change] update package.json
[new] util.js copied from  element
[unresolved] see test/unit/index.js @todo

build/webpack.test.config.js

@@ -0,0 +1,25 @@
+/**
+ * 用于单元测试
+ */
+
+var webpack = require('webpack')
+var merge = require('webpack-merge')
+var webpackBaseConfig = require('./webpack.base.config.js');
+
+
+var webpackConfig = merge(webpackBaseConfig, {
+  // use inline sourcemap for karma-sourcemap-loader
+  devtool: '#inline-source-map',
+  plugins: [
+    new webpack.DefinePlugin({
+      'process.env': {
+        NODE_ENV: '"testing"'
+      }
+    })
+  ]
+})
+
+// no need for app entry during tests
+delete webpackConfig.entry
+
+module.exports = webpackConfig