https://bugzilla.redhat.com/show_bug.cgi?id=1564270

Now that everything is prepared for qemu driver we can enable
parser feature to allow users define such domains.

At the same time, introduce bunch of tests to test the feature.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>