Add recent neutron extentions and IB support

Additions to Mellanox Plugin:
Add ML2 compatibility support.
Enable Infiniband Network Type.
Keep the compatibility to Linux Bridge Plugin to allow Network node deployment via Linux Bridge L2 Agent.
Add support for Host Port Binding and L3/DHCP Agent Scheduler.

Implements: blueprint mlnx-plugin-improvments

Change-Id: Ieca518bbd07a39258cd14ceeecd3f9d3e2b6f219
Fix a race condition in add_tunnel_endpoint()

If there are multiple OVS agents concurrently executing
'tunnel_sync' RPC call a race condition can occur
leading to insertion of two different TunnelEndpoint
entries having the same 'id' value.

Unfortunately, we can not rely on:
  - @lockutils.synchronized(), because a Neutron installation can use
    more than one API node
  - with_lockmode('update'), because it works differently in PostgreSQL
    comparing to MySQL and doesn't guarantee that no new rows have been
    added to the table since the select query was issued. Please take a
    look at http://www.postgresql.org/files/developer/concurrency.pdf for
    more details.

The proposed fix:
  - ensures there is a unique constraint set for 'id' column
  - wraps creation of a new TunnelEndpoint entry into a
    repeatedly executed transactional block (so even if a concurrent
    DB transaction has been flushed or commited earlier than this one
    we can handle an integrity error and try again, in spite of the
    specified transactions isolation level value)

Fixes bug 1167916

Change-Id: I62dc729d595f090436199d5e1b6b98a884ead7a5
Merge "Add recent neutron extentions and IB support"
Merge "Fix a race condition in add_tunnel_endpoint()"
Implement MidoNet Neutron plugin for Havana

Implement L2, L3, security groups, metadata server support for
MidoNet Neutron plugin for Havana.

blueprint https://blueprints.launchpad.net/neutron/+spec/midonet-plugin-havana

Change-Id: I0dd1a2ca17d760443c4c7a464a66b6d0a2cf194a