Cleaning some page animations

-> Fix jump when last page gets delted (issue 10908427)
-> Fade out empty screen
-> If the final page is empty, and that is the current page when
   spring loaded mode ends, animate back to the previous page
   and then fade out the final page. Examples: cancel widget
   or shortcut drop on the final page, scroll to final page and
   drop an icon into a the hotseat, etc.

Change-Id: I13438fb0af6555b6f0b511b7aff51b3972431438