advanced reboot: add soft reboot option

Adds a "Soft reboot" option which restarts zygote, as requested in JIRA
CYAN-3998

Change-Id: Ia6e5ed9b053e1c5ebd1fc55e5692858b97f7e0fc
Signed-off-by: Roman Birg <roman@cyngn.com>

Patchset: 2
http://review.cyanogenmod.org/#/c/67837/

Conflicts:
	core/res/res/values/cm_arrays.xml
	core/res/res/values/cm_strings.xml
	services/java/com/android/server/power/ShutdownThread.java
FB: Slimrecents background color && transparency [2/2]

Change-Id: Icf0259ce45d416364d6e7a7a8c2038f6c4c0cbde