overlay: Make cLock widget centered on default workspace

screenshot https://dl.dropboxusercontent.com/u/5779366/Screenshot_2013-04-12-22-21-14.png

Change-Id: I70cc193fb2c930b9d505525920a7a3533a41624e

Conflicts:
	overlay/cm/packages/apps/Trebuchet/res/xml-sw600dp/default_workspace_no_telephony.xml