Queues: redid the breakout control model so we can start up and subscribe to queues...

Queues: redid the breakout control model so we can start up and subscribe to queues without running through the complete site list, which is ok at 1k sites but too slow at 10k.
All breakout queues that we're going to need to listen to now need to be explicitly listed in $config['queue']['breakout'].

Until XMPP is moved to component model, this setting will let the individual processes work with their own queues:
$config['queue']['breakout'][] = 'xmpp/xmppout/' . $config['site']['nickname'];