cisco_ml2_apic_contracts table needs to set nullable=False on tenant_id column

[Henry Gessau]

In DB migrations the following is detected:
INFO [alembic.autogenerate.compare] Detected NULL on column 'cisco_ml2_apic_contracts.tenant_id'

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/108386

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/108386
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=6762acab9ca70bad843cdee542d816ad8e3cb908
Submitter: Jenkins
Branch: master

commit 6762acab9ca70bad843cdee542d816ad8e3cb908
Author: Henry Gessau <email address hidden>
Date: Mon Jul 21 10:35:41 2014 -0400

    Set nullable=False on tenant_id in apic_contracts table

    The cisco_ml2_apic_contracts table has a tenant_id field that is not nullable
    since it is the primary key. The HasTenant mixin does not allow setting
    nullable=False, so use sa.Column() explicitly for this.

    Change-Id: If8e96e76fad0bfcf2bfd71b0223624f1da4517c9
    Closes-bug: #1342756