Correct flake8 E711 and E712 violations

[Henry Gessau]

Enable flake8 checking for
E711 comparison to False should be 'if cond is False:' or 'if not cond:'
E712 comparison to True should be 'if cond is True:' or 'if cond:'

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/86494

[Openstack Gerrit (openstack-gerrit)]

Reviewed: https://review.openstack.org/86494
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=dda6c89202b015628f74101839301424001a6c63
Submitter: Jenkins
Branch: master

commit dda6c89202b015628f74101839301424001a6c63
Author: Henry Gessau <email address hidden>
Date: Wed Apr 9 22:49:50 2014 -0400

    Enable flake8 E711 and E712 checking

    E711 comparison to False should be 'if cond is False:' or 'if not cond:'
         comparison to None should be 'if cond is None:' or 'if not cond:'
    E712 comparison to True should be 'if cond is True:' or 'if cond:'

    Most violations were in DB queries. Replace as follows:
      False -> sqlalchemy.sql.false()
      None -> sqlalchemy.sql.null()
      True -> sqlalchemy.sql.true()

    Change-Id: Iff54747b70f504d5466cfdc6e2ec4d7a0f9ddb7c
    Closes-bug: #1305377