tests: Start DomainDescriptor tests

Adding some tests before fixing hashing implementation.

Change-Id: I3502d0db927abbc8a8fdd90f74db07eeb517e457
Signed-off-by: Nir Soffer <nsoffer@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/34620
Reviewed-by: Francesco Romani <fromani@redhat.com>
Reviewed-by: Vinzenz Feenstra <vfeenstr@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>