Themes: Use first asset entry for lockscreen wallpaper

The current implementation assumes the wallpaper will be named
either wallpaper.png or wallpaper.jpg.  If this is not the case
the wallpaper is not applied.  This patch implements the lockscreen
wallpaper the same way that the regular wallpaper is done.

Change-Id: I9f3dd299c1e61158fa53c163f7e42e21e2f9b1dc
HeadsUp: Fix resetHeadsUpDecayTimer.

    - If user has forced immersive mode through expanded desktop,
    we shouldn't hide the heads up notification quickly.

Signed-off-by: Roman Birg <roman@cyngn.com>
Signed-off-by: Adnan Begovic <adnan@cyngn.com>

Change-Id: I6ac015ce5c28216cafd3ce96f8d1993495b26897
Themes: Use default_wallpaper for HOLO lockscreen wp

Change-Id: I9c7fd29c99d13e811993eb9b3b045010431ccad0