MPLS Transport Profile support

[ne-vlezay80]

RFC:
https://tools.ietf.org/html/rfc7213
https://tools.ietf.org/html/rfc5921

The difference between MPLS-TP from the conventional MPLS in terms of development is that for point-to-point it is necessary to use the multicast address as the source of destination, and for point-to-multipoint use a unicast mac address.
To search for neighbors, use GAP.

[riw777]

Need to decide if this is a kernel or ldp thing -- need to think about where this goes. @donaldsharp will add to feature request page.

[donaldsharp]

Added to feature page