Base: [1/3] Customizable lockscreen & navring targets

This is a squashed commit, ported from CM:

Add GlowPadView extensions needed for lockscreen targets and nav ring
Author: Danny Baumann <dannybaumann@web.de>
Change-Id: I4f82fd3fe04ac16c6737d38b2473f2a533c5d326

Framework : Lockscreen - Customizable shortcuts
Author: Danesh M <daneshm90@gmail.com>
Change-Id: Ic3b935df5c0da35f31373d96943e442dc39cf11b

Add back navigation ring customization
Author: Danny Baumann <dannybaumann@web.de>
Change-Id: Iebe4ec7c2519b85cfd5189d060444764a50f3cf6
Merge "Base: [1/3] Customizable lockscreen & navring targets" into android-4.4