cLock: Listen for ACTION_ALARM_CHANGED

Change-Id: I97c92d5cebda1fb1c54cdd54b2b7e8f9ac383b14
JIRA: CYAN-1992
Issue: https://jira.cyanogenmod.org/browse/CYAN-1992
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>