sp: use setDomainsMap in reconstructMaster

The metadata access executed in reconstructMaster should be replaced
by the existing setDomainsMap. In order to do so we also need to set
the master domain (used by setDomainsMap) and temporarily set the
storage pool as secure (in the same way we do in create).

Change-Id: I0ce8ad258be09b40ee9ad06399cc841f374bf816
Signed-off-by: Federico Simoncelli <fsimonce@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/23385
Reviewed-by: Ayal Baron <abaron@redhat.com>