Kinetic scroll view fixes / changes

1. Mousewheel support for Firefox, IE
2. Fixes that problem whereby _currentTranslationX & _currentTranslationY are not being updated to reflect the current position of the view. Not updating this cause views to jump all over the place and appear broken.
3. Changes behavior of scrollBars to turn on only when the view is scrolled. This is needed for scrollviews with clickable children. eg. tableRows