Made 'shown' event compatable with both Twitter Bootstrap 2.3.2 and 3.0.0

The purpose of this commit is to make the Bootstrap Wizard compatible with both the earlier version of Bootstrap and the latest version without having to make any additional modifications. This is done by attaching to both the _legacy_ 'shown' event as well as the newer 'shown.bs.tab'. Since one or the other will be triggered, there should be no conflict by listening for both,