ZeroMQ integration for route output

[Sam Russell]

Hi all,

I've been working on integrating BIRD into some SDN packages
(VANDERVECKEN/RouteFlow, ONOS), and as part of this I've built zeromq
in as an option. It's still beta, but you can stand up BIRD and poll
the ZeroMQ socket and it'll reply with a route table dump in JSON.

Keen to hear what people think

https://github.com/samrussell/bird/tree/zmqintegration

Cheers
Sam