This adds a new window feature -- FEATURE_SWIPE_TO_DISMISS -- and a
theme attribute to activate that feature. When the feature is
activated, a SwipeDismissLayout is inflated as the DecorView layout.
SwipeDismissLayout intercepts touch events and steals ones that are
large swipes to the right if its children don't. PhoneWindow registers
handlers that listen for these swipe events, translate the window when
necessary, and finish the activity at the end of the gesture.
Change-Id: I512e758f3c3ffd3b353dba3b911c0e80a88d6f5f
ca6234e084