SAFI 129 NLRI compliance with RFC 6514

The NLRI format available for BGP VPN multicast is changing from the de facto format of SAFI 128 to SAFI 129 as defined in RFC 6514. SAFI 128 uses length, label, prefix. SAFI 129 uses length, prefix. To use SAFI 129, enable the rfc6514-compliant-safi129 statement at any of the following hierarchy levels: [edit protocols bgp], [edit protocols bgp group group-name], or [edit protocols bgp group group-name neighbor address].