Fix erroneous fk columns created by bad foreign_key syntax

This PR is a fix for Issue https://github.com/cloudfoundry/cloud_controller_ng/issues/48

This fix breaks my Oracle pull request.  So, once this is merged I will immediately update my Oracle support PR which I'm still hoping can be merged soon.

It should safely fix Schemas that have the problem and ignore Schemas that are new and created with the fixed create_permission_table syntax.