tests: split API schema conformancy tests

this patch splits the VM API schema tests from the main unit tests body
with no functional changes.

Change-Id: I38d1d68ee1a556a9a1f484f436217a463c8705aa
Signed-off-by: Francesco Romani <fromani@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/28800
Reviewed-by: Piotr Kliczewski <piotr.kliczewski@gmail.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>