Runtime toggle of navbar

This adds the framework support for enabling the Navigation bar
on devices with hardware keys. It is toggled from Settings, and
depends on device-specific support for the KeyDisabler hardware
control

Change-Id: I88fecb2ca1e8613591c327a93f53909b00239cd8

Conflicts:

	core/java/android/provider/Settings.java
	packages/SettingsProvider/res/values/defaults.xml
	packages/SettingsProvider/src/com/android/providers/settings/DatabaseHelper.java
	packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java
	policy/src/com/android/internal/policy/impl/PhoneWindowManager.java
Don't let apps disable the SIM PIN entry screen.

As the user (who controls the app behaviour after all) likely doesn't
see the PIN screen as a lock screen (he likely wants telephony) and the
PIN screen is not shown on a timer-driven basis, it should be treated
specially.

Change-Id: I8d48ab5f097bc926f67eab5835d9b5f1e581db15
Don't recreate keyguard for MCC/MNC changes.

Change-Id: I9e5dfdb12df522dc7dd50c26f35aba26b1bbe44e
FaceUnlock: Check if faceunlock is disabled

JIRA: CYAN-3622
Issue: https://jira.cyanogenmod.org/browse/CYAN-3622

Change-Id: Iaf656f1aecb72610a46183294de25151e8df4b05
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>