Show/hide FloatingActionButton improvements

We now have an explicit show()/hide() method so that
developers can use the spec'd animation.

Also fixed an issue where the FAB would be animated in,
overriding the developers set vsibility.

BUG: 21652571
BUG: 21652427
BUG: 21689751

Change-Id: I248d49b812c018e6d46a6ccde262433868ae272e
6 files changed