add shutdown animation

- Run shutdown animation during shutdown if surfaceflinger is
  available / running.
- services necessary for animation should be added to animation
  class.
- Keep debugging tools while non-critical services are terminated:
  logd, adbd, tombstoned

bug: 36526187
Test: many reboots

Change-Id: I758f700a622c6005f3df9f29de2b55270055ad4d