Modify the PushBackTransition example to use connected properties instead of multiple springs.
Modify the PushBackTransition example to use connected properties instead of multiple springs.

Summary: This helps connect the example with the interactive version which uses connected properties to build a more complex transition.

Reviewers: O4 Material Apple platform reviewers, O2 Material Motion, #material_motion, markwei

Reviewed By: O4 Material Apple platform reviewers, O2 Material Motion, #material_motion, markwei

Tags: #material_motion

Differential Revision: http://codereview.cc/D2979

material-motion/material-motion-swift,material-motion/material-motion-swift