Add missing db model changes related to nuage plugin

[Ronak Shah]

Due to decomposition of plugin work initiated during K release, nuage plugin have gone through much changes without them being incorporated upstream. But as per the decomp spec guideline, we need to keep migration and model definition upstream.

So need to add new schema along with migration script into K release.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/159281

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/159281
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=2387f23f12fdc546df0a160ca791d00ce492a795
Submitter: Jenkins
Branch: master

commit 2387f23f12fdc546df0a160ca791d00ce492a795
Author: ronak <email address hidden>
Date: Wed Feb 25 14:55:18 2015 -0800

    Adding DB model changes for Nuage Plugin post decomposition

    Due to decomposition of plugin work initiated during K release,
    nuage plugin have gone through much changes without them being
    incorporated upstream. But as per the decomp spec guideline,
    we need to keep migration and model definition upstream.
    So adding new schema along with migration script into K release.

    Change-Id: Ia825c764917b15910bae232edc340fa315b9ffab
    Closes-bug: #1424113