Modified first animation and visibility change behavior for ViewFlipper

 - Where previously ViewAnimator only exposed inAnimation and outAnimation as
   XML attributes, modified to also include the animateFirstView flag so that
   widgets can optionally choose to omit the animation for the first child
   view.

 - Changed the behavior of ViewFlipper so that simple visibility changes do not
   trigger extraneous and distracting animations.

Change-Id: I34b3abad33102978a94f0aed5aaab9af30ba49c7