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
Merge "Add recent neutron extentions and IB support"