Make LayoutTransition.setInterpolator() actually do something

Previously, you could set a new interpolator on a LayoutTransition object,
but it wouldn't have any effect, since the value was only used at construction
time. This change makes the intended behavior work, byt assigning that
new interpolator to the appropriate animations when they are run.

Issue #11163487 LayoutTransition.setInterpolator() has no effect

Change-Id: I1b390a30c008ac2bf26491dc352e28f276357388