PieService: add support for multiple activations.

Change-Id: Iec71a85e05cdde7392a297b93ca64d0c820df599
Allow showing statusbar on top of fullscreen window.

Swipe from top of the screen to show statusbar.
Statusbar will automatically disappears after 2 sec.

PS7: Also show statusbar when user moved finger far enough.
PS8: Compatible with Expanded desktop.
PS12:
  Fixed button in statusbar.
  Don't hide statusbar while expanded.
  Hide statusbar after collapsed.
  Disabled by default.
  Some small fixes.
PS19: Works through PieService.
PS20: Fixed class and variables naming.

Change-Id: I59bd022be6eb065ec6b9361213cc4fddc065b925

Conflicts:

	policy/src/com/android/internal/policy/impl/PhoneWindowManager.java