cr-restore: "post-resume" hook introduced

This hook is called at the very end, when everything is restored and processes
were resumed.
Can be used for some actions, which require operation container, like
restarting of systemd autofs services.

v3:
Call "post-resume" scripts before detach option check (to make sure, that
restored process(es) are still alive

v2:
Remove code chunk, escaped from debugging

Signed-off-by: Stanislav Kinsburskiy <skinsbursky@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>