Adding TimeAnimator capability (hidden for now)

This new class allows listeners to receive callbacks with elapsed time
that are sent on the same animation updates as other animators in the system.
It will allow simulations that go beyond the current animation system while
handling the actual animation timing system and ensuring that those
simulations sync up with other typical animations.

Change-Id: Iac91c39634218793f6598a7dec5ed71dc9630258