GEL Integration (2/2)

Launch search from extra panel to mimic Google Launcher.

Changed Trebuchet to build against CM instead of the AOSP SDK.
Added support to swipe left from the home screen to enter Google Now, if it is installed.
A right swipe will return the user to the home screen.

Change-Id: Ia1a77fedea7e67bcd54a6b6d66099f8366d6b1dc