Themes: Use default_wallpaper for HOLO lockscreen wp

Change-Id: I9c7fd29c99d13e811993eb9b3b045010431ccad0
ExpandHelper: Performance improvement during expanding

- Reflects on Hover mainly
- Add an helper to get natural height

Thanks to Kiril Mikos @mik9 http://review.cyanogenmod.org/#/c/66676/

Signed-off-by: Carlo Savignano <stevewatersy@gmail.com>
HOVER: Respect screen limits when adding view

As for what @Decad3nce reported here http://review.cyanogenmod.org/#/c/66654/
we shouldn't keep FLAG_LAYOUT_NO_LIMITS so view doesn't exceed the screen limits.

Thank you Adnan :)

Signed-off-by: Carlo Savignano <stevewatersy@gmail.com>
Change-Id: Ifcbc4a1143362e1b7dd40e710126060688c894b9