Fix post_start_hooks entry point, add purge to setup hook

post_start_hooks was calling post_setup_hooks,
which is a misnomer. post_setup_hooks should also
call purge because it is necessary during upgrades.

Change-Id: Ic8731f185338b6febd9c543f837ffed2abec80a5
Partial-Bug: #1349287
Merge "Fix post_start_hooks entry point, add purge to setup hook"