Use neutron-db-manage instead of alembic

* A new script was added to upgrade the neutron tables. Use this script
  instead of the alembic command directly

Change-Id: I3f89b10cc0c2bd6992279a64ad73ff445acd98bd
Signed-off-by: Joe Mills <joe@midokura.com>
Merge "Use neutron-db-manage instead of alembic"