Fix 6398209: General animation improvements for swipe to search

This cleans up the animation for swipe to search from the navbar.  In particular:
1. Wait for initial animation to finish if gesture was too quick.
2. Better fade animation
3. Hide background and fade in when ring is selected
4. Smoother target and outer ring animation when switching between states.

Change-Id: I401197760cf9f06b6ff3e1cdb80bee86a03ef276