SystemUI: Add global reboot option

Add global reboot option when long press power key and confirmation dialog
when user chooses to reboot device.

Change-Id: I23286cb655a4fead8dfc450f08f27d9588e47686
Signed-off-by: Chet Kener <Cl3Kener@gmail.com>

Conflicts:
	core/res/res/values/symbols.xml

Signed-off-by: Chet Kener <Cl3Kener@gmail.com>