Fix ScrimInsets* classes to use ViewCompat.postInvalidateOnAnimation

Change-Id: I7ef8e65110fa861605f4d4f9aebb10ac775c29b8
Merge pull request #62 from romannurik/master

Fix ScrimInsets* classes to use ViewCompat.postInvalidateOnAnimation
Merge branch 'master' of https://github.com/google/iosched