The 'connection' parameter should be non mandatory when 'connectmanually' is set to true

[zc-tired]

When 'connectmanually' is set to true, Vue.use () should be able to set the socket link to be empty. When calling $connect, an error will be thrown when the protocol link address is continued to be passed in when the link is not passed in when mounting to Vue and no link is passed in when $connect... Now I operate like this when mounting = > Vue.use (websoket,'ws://',{connectmanually:true})