ircbot_connection should be a gen_server

[gdamjan]

ircbot_connection should be a gen_server, so that it reloads itself automatically.
also, that way it can be supervised by a supervisor (which doesn't do anything now).

the whole supervisor thing needs to be re-thought. The ircbot_app should probably run the ircbot_fsm (gen_fsm), ircbot_plugins (gen_events) and ircbot_connection (gen_server) in a supervisor, and connect them together. The last thing is not so easy without registering the gen_* with a name, which I have avoided till now.