Themes: add ability to theme quick settings battery tiles

This is to make the battery tiles more uniform to the rest
of quick settings and also allow the background to be themed

http://i.imgur.com/AA5bkMK.png

Change-Id: Iec03572a0fa3619d2652f30b6c260a278ed0c86b
HeadsUp: Respect system decorations when adding view.

    - FLAG_LAYOUT_IN_SCREEN ignores system decorations, so
    a heads up view in landscape would end up underneath the navbar

    - FLAG_LAYOUT_NO_LIMITS allows the window to exceed the screen
    limits all together

      Removing both these flags makes Heads Up respect both system
    decorations and the screen limits.

Change-Id: I6f111e1c5701d493979be0cb596f11bc1b437fda