Split out jabber handling to equivalent service to smsd

Putting the actuall jabber in alertengine has proven to have its flaws. As such I propose to create a jabberd service to handle sending jabber messages in the same way that smsd handels sms-sending. This change will increase the number of moving parts and complexity of message sending in NAV, but it will also ensure the problems with the jabber service doesn't affect other parts of alertengine.