tests: Test schema validity

Add a simple test case to check schema validity.  For now, we just call the
schema parser and make sure it doesn't raise any exceptions.

Change-Id: If7680aaf8eb41546e3a8d38e405c7f9ed8bdd192
Signed-off-by: Adam Litke <agl@us.ibm.com>
Reviewed-on: http://gerrit.ovirt.org/10050
Reviewed-by: Douglas Schilling Landgraf <dougsland@redhat.com>
Reviewed-by: Saggi Mizrahi <smizrahi@redhat.com>
Reviewed-by: ShaoHe Feng <shaohef@linux.vnet.ibm.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>
Tested-by: Dan Kenigsberg <danken@redhat.com>