pep8: storage cleanups for pep-1.5.x

storage/* is now pep8 1.5.x clean.

Change-Id: I49d4e4e59101ea54759a700644f04c9400fe2349
Signed-off-by: Francesco Romani <fromani@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/26424
Reviewed-by: Federico Simoncelli <fsimonce@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>