9. core : Change HibernateVmCommand to persist all placeholders

    This patch changes HibernateVmCommand to persist all
    async task placeholders before executing the command on vdsm.

http://www.ovirt.org/Features/AsyncTaskManagerChanges_3.3
Change-Id: Iff09771c32381805b59130cc5425907b7946cd63
Signed-off-by: Ravi Nori <rnori@redhat.com>