DeskClock: Add option to hide AlarmClock Icon in StatusBar

If somebody does not need to be reminded by an icon in the status bar
of an enabled alarm. You can switch it off.

PS2: remove whitespace

Original commit: http://review.cyanogenmod.org/#/c/29106/

Change-Id: I5a877cbeea21083470360b6ce14df141db1b8fc7