Fix show, hide and toggleView methods in transition module

Deals with - http://yuilibrary.com/forum/viewtopic.php?p=36173
Checking for type instead of assigning empty callback.
Merge branch 'fix/transition' of https://github.com/prajwalit/yui3 into prajwalit-fix/transition
Apply toggleView() with arguments to handle overloading.
Move to tests/unit.
Move to tests/unit.
Merge pull request #1 from msweeney/prajwalit-fix/transition

Prajwalit fix/transition
Merge branch 'fix/transition' of https://github.com/prajwalit/yui3 into prajwalit-fix/transition
Merge branch 'prajwalit-fix/transition' into dev-master