Cache routing component

1. effect ：
   
   Keep the routing components not shown mounted , Not destroyed .
    
2. How to use , In the to cache router-view Area wrap keep-alive label
   
   
   
   Be careful ,include Attribute News It's the component name , Here is the designated cache News label
   
   If you don't specify , By default, all components displayed here are cached
   
   If you want to cache multiple arrays