Squashed commit of the following:

commit 62db6d58cafec74439d4bcb4ace8e4cc0741f5d4
Author: Marc Nilius <marc.nilius@otrs.com>
Date:   Mon Jun 24 14:00:49 2013 +0200

    Fixed some issues after QA.

commit 7f7d63c2c29de3122573e5ccd3325b197f8aae38
Author: Marc Nilius <marc.nilius@otrs.com>
Date:   Thu Jun 20 16:36:17 2013 +0200

    Removed FixedTableHeader and renamed some CSS.