[TASK] Border line between groups in backend wizard

Change-Id: I277bf4785e0a2085a92e6d24ee004f95907f6f8a
Reviewed-on: http://review.typo3.org/32235
Reviewed-by: Xavier Perseguers <xavier@typo3.org>
Tested-by: Xavier Perseguers <xavier@typo3.org>