Pool Manager - Pool Manager Proxy Backend and Devstack

- Implemented a pool manager proxy traditional backend
- Incorporated pool manager into Devstack
- Changed pool_name to pool_id in [service:pool_manager]

To use pool manager in Devstack add to the localrc:

    ENABLED_SERVICES+=,designate-pool-manager
    DESIGNATE_BACKEND_DRIVER=bind9_pool

Change-Id: I66b81e30067c7c5ff4f1d7c8fd2eecc3b0a3012c
Partially-implements: blueprint server-pools-service
Merge "Pool Manager - Pool Manager Proxy Backend and Devstack"