[Settings] Ability to turn HW keys on/off on supported devices (2/2)

- Enabled through overlay in device repo

Change-Id: Ieecbec6d25427803c3d504620d700fe9955c02d7

Conflicts:
	res/values/cr_strings.xml
	res/xml/button_settings.xml
	src/com/android/settings/cyanogenmod/ButtonSettings.java
Revert "Settings: Implement Dynamic System Bars (2/2)"

This reverts commit 513e0aed54e49e3a403afd89ee72b9ec3a481d40.

Conflicts:
	res/values/bs_strings.xml

Change-Id: Ic68cccdf510d087d04e21e4c60ee457b32760b4b