Add lockscreen rotation as an optional rotation setting (2/2)

This will allow the user to select wether or not to use the
rotation settings for the lockscreen.  This is dependent
upon the rotation setting being checked.

Signed-off-by: Michael Bestas <mikeioannina@gmail.com>

Change-Id: If45c13a395e0d71b7c4cdcf484a6b8cef964ee37
JIRA: CYAN-339

Conflicts:
	src/com/android/settings/DisplaySettings.java