Add Active Display to AOKP [2/2]

* Amazing work by 0xD34D
* Since he encouraged cherry-picking this, and I was very interested in
     porting this from Moto X, thus I am introducing it here

Signed-off-by: Brandon McAnsh <brandon.mcansh@gmail.com>
Change-Id: I134aee969659e62051e12561fa09759385b9654f
Active display: allow hiding low priority notifications

Change-Id: I95e9898ae2046391cdc5f151d757618b4f1c089e