Handle actor stop

[albireox]

Right now when we shut down the actor from the command line (whether it's with --debug or with the daemon) the connection to the Archons is not closed. This seems to cause that if you reconnect soon after and try to write the config, sometimes that raises and error.

I should handle this better by catching the SIGKILL/SIGTERM signal and closing the connection to the controllers before exiting. This should be added to ArchonActor.stop() as part of the shutdown. For the daemon I'm not sure if handling the signals will be enough, but it's the first thing to try.