base

Refactoring and unifying TaskView animations.

- Adding notion of a TaskViewAnimation to animate a TaskView to a
  specific TaskViewTransform
- Refactoring task view enter/exit/launch/delete animations into
  a separate class so that we can improve them easier
- Removing individual TaskView view property animations in favor
  of using the existing TaskStackView stack animation. This ensures that
  we don't have to add separate logic when animating TaskViews.  It is
  all handled by the TaskStackView now.
- Breaking down the TaskStackView synchronize method into binding
  TaskViews and updating them to transforms.  This allows us to
  synchronously update in many cases and is cleaner than the many
  request* calls.

Change-Id: Ib26793568a14e837e6782358155f21158a133992