Add start/endTransition events for CHANGE transitions

There was already a mechanism for sending out events for LayoutTransition
when animations started or ended, but the implementation only sent out events
for the appearing/disappearing animations. This fix provides callbacks to
listeners for the CHANGE_APPEARING and CHANGE_DISAPPEARING transitions, too.

Change-Id: Icfb8cc1c20d2df3e4a817255e96c9d0e94c1d8c4