Adds Brocade Plugin implementation

blueprint brocade-quantum-plugin

This plugin is meant to orchestrate Brocade VCS switches
running NOS, examples of these are:
   1. VDX 67xx series of switches
   2. VDX 87xx series of switches

Change-Id: Ia8c91ba0e70d3dc7fa79e7f0e09f869542846954
Merge "Adds Brocade Plugin implementation"