Lockscreen: option to use carousel animation when switching widgets (1/2)

This will add the option to use a carousel animation when
switching betweeen the widgets on the lockscreen.

Change-Id: I1ad69810b5f012b56cb047dce47a39c1e8f542a2
Signed-off-by: Dirk Rettschlag <dirk.rettschlag@gmail.com>