change view classname for tabs

/cc @sshillo @will2357 @nbryan @ciniglio @mgamba 

The modal and tabs views both use a 'view' class, making it quite tricky to nest tabs within a modal.  As far as I can tell, no CSS or jQuery code in our app depends on the tabs' 'view' class, so this change should be entirely non-breaking.

But... I obviously could have missed something?