Add service-provider-feature for bgpvpn-vni
Add service-provider-feature for bgpvpn-vni

This feature is added to communicate to OpenDaylight driver that vni
attribute is supported in bgpvpn resource in OpenDaylight.

This review depends on the following reviews.
https://git.opendaylight.org/gerrit/#/c/63405/
https://git.opendaylight.org/gerrit/#/c/77250/
https://review.openstack.org/#/c/614428/

Change-Id: I3bfb0b7844455fb908955d3949e52b71125c7826
Signed-off-by: Ashik Alias <caf1949fa4c866422856c2b3a3dc3a962ad1c3b2@ericsson.com>

opendaylight/neutron