Add a fix for input-group of tw-bs

When you have a input-gruop in bootstrap3, the parent is matched incorrectly, beacuse bs3 now use a div for input group, and the parent should be the parent of these div. This is a little fix for that, check if parent has class "input-group", and get's the correct parent
Merge pull request #168 from eleazan/patch-1

Add a fix for input-group of tw-bs