Cleanup the G_LOG_DOMAINS we use especially for debugging

 * cockpit-protocol: low level stuff, very busy repetetive messages
   produced by both cockpit-ws and cockpit-agent processes
 * cockpit-ws: web service higher level
 * WebSocket: the web socket code (separate from cockpit)
 * cockpit-agent: the agent specific code

You'll likely need to 'make clean' after applying this patch.

Closes #569
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>