相比vue-loader V14, V15配置上有重大变化，需要在webpack.config.js中声明以下内容
参考vue-loader官方文档
// webpack.config.js
//Vue Loader v15 now requires an accompanying webpack plugin to function properly
const VueLoaderPlugin = require('vue-loader/lib/plugin')
module.exports = {
// ...
plugins: [
new VueLoaderPlugin()
]
}
