Don't fail hotplugNic operation when after hook fails

Change-Id: I8df7812cee7632addf87f7dc1c49182f55c51e8e
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1015171
Signed-off-by: Yaniv Bronhaim <ybronhei@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/20876
Reviewed-by: Antoni Segura Puimedon <asegurap@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/20901