Maximize animation when activity is relaunched.

This is the first step towards maximize operation animations. It
builds upon preserving old window and starts clip+translate animation
of the new window from the frame of the old window. It mostly uses the
existing infrastructure, expanding the idea of opening apps list to
include also relaunching apps and treating maximize operation as an app
transition.

Change-Id: I7be402bd329c2fe5bf7d53a2a910532286a8b194