require.contex 自动话引入

https://cn.vuejs.org/v2/guide/components-registration.html#%E5%9F%BA%E7%A1%80%E7%BB%84%E4%BB%B6%E7%9A%84%E8%87%AA%E5%8A%A8%E5%8C%96%E5%85%A8%E5%B1%80%E6%B3%A8%E5%86%8C