convert sampling classed to new style classes

The use of old style classes is discourged in modern Python

Change-Id: Ice50e7a51d6b18e490a14a9fb088e721cbb7747c
Signed-off-by: ibarkan <ibarkan@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/36178
Reviewed-by: Francesco Romani <fromani@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>