Updated openstack/openstack
Project: openstack/neutron  ada67a412095d535a0c682d26fb3201925bd8445

Refactor test_migration

test_migration contains some methods like overriding compare_server_default
and compare_foreign_keys that was added directly in ModelsMigrationsSync
class in oslo.db only in 1.1.0.

Also as now migrations refactoring is fully finished, there is no
need to have separate classes for each plugin.

Closes-bug: #1393691

Change-Id: I65b40fe52c2c6f4bae88e125bd1ee501aaa24114