Adding Yang Model for Openstack Host Configuration

Adding Yang Model for Openstack Host Configuration

Adding YANG module to define host configurations that is used
in specifying the physical host type and configuration
for host system. Examples of host type are network node,
compute node, etc. Example for configuration is a Json string
like {'supported_vnic_types': 'VNIC_NORMAL', 'vif_type':
'VIF_TYPE_VHOST_USER', ….} etc. This information is read
and populated by networking-odl in agent_db in Neutron and
is used by Openstack Neutron scheduler. Supports features
like Port binding and Router scheduling.

Change-Id: I630e6d88f1b1beb6d5e442ccddf6a5d7137a5a51
Signed-off-by: Ritu Sood <ritu.sood@intel.com>