update dev script

Author: yyx990803

build/webpack.dev.config.js

@@ -0,0 +1,18 @@
+module.exports = {
+  entry: './src/index.js',
+  output: {
+    path: './dist',
+    filename: 'vue-router.js',
+    library: 'VueRouter',
+    libraryTarget: 'umd'
+  },
+  module: {
+    loaders: [
+      {
+        test: /.js/,
+        exclude: /node_modules/,
+        loader: 'babel?optional[]=runtime'
+      }
+    ]
+  }
+}

package.json

@@ -4,7 +4,7 @@
   "description": "A router for Vue.js",
   "main": "lib/index.js",
   "scripts": {
-    "dev": "npm run serve & npm run serve-test",
+    "dev": "npm run serve & npm run serve-test & webpack --watch --config build/webpack.dev.config.js",
     "lint": "eslint src build test/e2e test/unit/specs",
     "unit": "./node_modules/karma/bin/karma start build/karma.config.js",
     "build": "babel ./src --optional runtime --out-dir lib && webpack --config build/webpack.build.dev.config.js && webpack --config build/webpack.build.min.config.js",