[2/2] Add lockscreen rotation as an optional rotation setting

Taken fom Omni: https://gerrit.omnirom.org/6440
Who takes it from: http://review.cyanogenmod.org/#/c/55016/

PS2: Fix patch set info in commit message

Change-Id: Icfd4344ffaf6987fe51b2a28df47593d9b3b3c0c

Conflicts:
	core/java/android/provider/Settings.java