ring unlock: (1/2) enable unlock on middle ring

Allows the user to change the layout of the ring lockscreen through
two new toggles in cmparts lockscreen style menu.

One toggle switches the unlock and custom app rings putting the unlock in the middle
and the custom app on the left. This option is available when custom app is checked in
cmparts.

The second toggle provides a minimal ring lockscreen with one ring in the middle to
unlock and hides the left and right rings. This option is only available if custom app is
unchecked in cmparts.

http://review.cyanogenmod.com/8480 and http://review.cyanogenmod.com/8479

Change-Id: Ief978a06f8ebc59271f33425738a5458e078200f