Update radial time picker styling, clean up code

Uses activation color for picker background. Removes bounce animation
when switching between hour and minute pickers. Improves touch handling
when touch moves outside the circle. Cleans up use of string in XML
where float should have been used. Fixes layout so that padding can be
adjusted.

Change-Id: Ibc8e087a83ca522272cdcd434b36cf38583bf541