ovirt-image-uploader: fixing usage of API SDK insecure parameter

Python SDK insecure parameter simply skips hostname validation,
it still gives errors if we also pass an unmatching CA cert.

Change-Id: I02f96fb2053c543e1c54dc84921da75823282509
Bug-Url: https://bugzilla.redhat.com/1136434
Signed-off-by: Simone Tiraboschi <stirabos@redhat.com>