core: Provide informations about fencing in oVirt

This patch adds missing logging in both log file and audit log for
fencing flow.

Change-Id: I3f9aa1711f9b47b7a5a3b805da4002e3fbbe24be
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1070674
Signed-off-by: Eli Mesika <emesika@redhat.com>