Canceling pep8 and pyflakes check for stable branch

pep8 and pyflakes versions got updated and we don't want to modify the
stable code regarding to the new rules they declare. Therefore, we
cancel those checks during the make process.

Change-Id: I79ca63546a45e47dbebe9726b82b53053937ffae
Signed-off-by: Yaniv Bronhaim <ybronhei@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/30897
Reviewed-by: Dan Kenigsberg <danken@redhat.com>
Reviewed-by: Sandro Bonazzola <sbonazzo@redhat.com>