Bring back Density changer from AICP 4.3 base

Old AOKP one, don't know the author, sorry!!!
I'm dragging this from base to base lol

AICPfy lp5.0:
- Added link to dpi modded XDA thread on tap
- Cleaned it up a bit
- Menu item can be added later if needed

Change-Id: I7f16c7c3d32c58cc614e0d6b1da25d8389c582bd