lockscreen: new Ring style - CMParts (2/3)

Introduces a new Ring style - 2 rings on left/right to unlock/silence.
1 ring in the middle to launch up to 4 custom apps.
Rings can be dragged anywhere on lockscreen - not just in one direction.
Unlock/silence rings are triggered by dragging the ring far enough away from its neutral position.
Custom apps are triggered by releasing the middle ring while over the app icon.

Demo video: http://www.youtube.com/watch?v=VnQzT9QyJFQ

EDIT: added ability to un-set custom apps
EDIT 2: added values to translated arrays (please let me know if any translations are off -- I only used Google Translate)
EDIT 3: changed the way custom apps are added/set

Change-Id: If48f45ba14c4096bc8d1077b386b2bdb2b2e7b64