Add extension for control channel.

To operate server, control channel is created. And new extension class
"Server Operator" is also added.

Custom queue can be created before binding queue and so on.
Implement control channel to connection

And reconnection watchdog supports channel update.
Now only control channel.
Add and modify tests
Improve error log
Add interface used from ServerOperator

To keep secure, interface class is added. Using this, channel instance
is passed to ServerOperator.