Squashed commit of the following:

commit a382e08d7cd226f3ea48f87738b335dde21ed2d0
Merge: 658ac65 417cabf
Author: Marc Nilius <marc.nilius@otrs.com>
Date:   Mon Jul 29 10:14:23 2013 +0200

    Merge branch 'master' into feature-serviceslamandatory-mn-master

commit 658ac6537818a0c4b30413382fedcd4c41f30834
Author: Marc Nilius <marc.nilius@otrs.com>
Date:   Mon Jul 22 17:46:45 2013 +0200

    Added possibility to have mandatory Service and SLA fields in many screens.