Base] Nav bar tweaks

Ported from crDroid to Validus
- Toggle on/off (CyanogenMod alredy did but only for hw keys devices).
crDroid allow all devices to do that for those using PIE apps.
- Nav bar dimensions (height and width)
- Here we also automatically reverts CyanogenMod navbar toggle: b70cda7
PS: THIS COMMIT IS A SQUASHED PORTED FROM crDroid KK and 99% od the
codes are from SlimRoms.