Alembic should use oslo_db facades
Alembic should use oslo_db facades

This fixes the issues of alembic going around oslo_db and
not passing additional options to the engine.

Closes-bug: #1700634
Change-Id: Id4ec71d7868fec93e3ee793e6e3b8888f8c34c92

openstack/glance,openstack/glance,openstack/glance