because there isn't a THING like separator in bootstrap code removed

The used bottom group was wrong because it is something different than a separator (or divider) and since there isn't a something like a separator we don't have HTML code for that.

related tracker item: http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_id=8103&tracker_item_id=31588