engine : Reason does not get updated when trying to shut down a VM

When trying to stop the VM while it is
powering up or shutting down, the reason
comment does not get saved in the DB

Change-Id: I8f70177206de3fd3081826ea898ab2a7fb87357b
Bug-Url: https://bugzilla.redhat.com/1114903
Signed-off-by: Ravi Nori <rnori@redhat.com>