migrate_utils does not migrate data if created_at column does not exist

[Kanagaraj Manickam]

sqlalchemy utils 'migrate_data()' does not migrate the data from old table to new table if the created_at field does not exist. This bug is filed to fix it so that it could be used for all tables.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/169678

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/169678
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=3d86095b766158b5effe1bf7547857b876958517
Submitter: Jenkins
Branch: master

commit 3d86095b766158b5effe1bf7547857b876958517
Author: Kanagaraj Manickam <email address hidden>
Date: Wed Apr 1 15:28:33 2015 +0530

    Fixes migrate_data utils to avoid created_at filed

    migrate_data utils does not migrate table data if
    table does not have column created_at field. It
    fixes this issue.

    Change-Id: Id179b295d8f0e0644420fb589baa5341d3020c7f
    Closes-bug: #1439094