Updated openstack/openstack
Project: openstack/requirements  7ebdaf52da82aa67f917b3aff0cfc2d37f97e408

Set alembic>=0.7.1

Alembic 0.7.1 contains some new functions like autogeneration of
foreign keys that are important and can reduce some code in neutron
and oslo.db

Change-Id: Ifc618a63ee0df6ac5c1b3a2b2f4176ebb9a1e080
Related-bug: #1398417