OpenDaylight Networking SFC Port Pair REST APIs

OpenDaylight Networking SFC Port Pair REST APIs

This patch defines REST API's in Neutron Northbound project
for the networking sfc port pair APIs and implementation of
the translation code to convert these REST API data to the
networking-sfc Yang models. These Neutron Northbound REST
API's are defined based on the OpenStack Networking-SFC Flow
Classifier APIs available at following URL.

http://docs.openstack.org/developer/networking-sfc/api.html#rest-api

Signed-off-by: Anil Vishnoi <vishnoianil@gmail.com>
Change-Id: Ie8b3bf725e492443ac4b0056c255a71e16b1635a