engine: Log unsupported network update

When hosts need to be updated on an unsupporting data center, an audit
log will be sent that specifies that the automatic update will not be
happening.

As specified in:
http://www.ovirt.org/Features/MultiHostNetworkConfiguration#Events

Change-Id: I9b37fbdec5134b3131c1cafb1cd9e0596c2efb74
Bug-Url: https://bugzilla.redhat.com/1055161
Signed-off-by: Mike Kolesnik <mkolesni@redhat.com>