allow forcing HighEndGfx mode

people have already started fipping the lomRam prop to enable
transparent status bar, this will enable it with fewer
repercussions

Change-Id: Ied6de65276425fa1e7db0bf9da35f1932a355172
Allow changing screen-off animation (1/2)

* Allow enabling/disabling screen-off animation
* Allow selection between fade & crt effects if the device allows it

Change-Id: If6bb9afd7a753e1df013e88f7f39cea94e8fe565