Discover/Import Servers Inventory and hardware info into Contrail-Command

# 1. Introduction
Tungsten Fabric supports discovery and ZTP of network devices. To properly configure underlay for the infrastructure servers (controller/computes), Tungsten Fabric needs to know about the connection details of servers and switch ports. Also for baremetal workload, details about the baremetal hardware needs to added manually as of now. In case of ZTP, discovery of servers and auto-adding them to Tungsten Fabric database should be provided.

# 2. Problem Statement
Adding Servers for provisioning Tungsten Fabric or adding baremetal nodes to Tungsten Fabric database is a manual task as of now. With 100 of infra nodes/baremetal nodes to add, it become cumbersome to use UI. Also for baremetal nodes, all hardware detail needs to be known and has to be entered.

So there is requirement to automate this portion of the ZTP and discover all possible servers

### Use Case:
Server Discovery will enhance the capabilities of the Tungsten Fabric to auto-add the servers and its hardware details, network connections, capabilities to Tungsten Fabric database. Also with possible integration of Tungsten Fabric with other tools, this may be used for re-imaging the servers and bringing the servers with needed OS to provision controller and computes. Also this will provide connection details of baremetals to contrail, which will configure the switches for providing underlay connectivity.