Include alembic migrations in module
Include alembic migrations in module

Explicitly include all alembic data in installed python module,
ensuring that installations directly from git repositories are
fully functional when compared to use of sdist generated tarballs
from tarballs.openstack.org or pypi.

Closes-Bug: 1627656

Change-Id: Ieb4272bdbf65e4b63a0e8d875847d299999470c2

openstack/networking-odl,openstack/networking-odl,openstack/networking-odl