Observe --net-alias argument to docker run

[awh]

Docker 1.10.0 added a new --net-alias argument to docker run - the proxy should intercept this add the additional records to weaveDNS.

[rade]

This opens up an annoying feature gap between weave run and docker run-via-the-proxy. Should we parse --net-alias in weave run?

Btw, the proxy (and CLI, if we do the above), needs to strip the net-alias from because

$ docker run --name=foo --net-alias=bar -ti ubuntu
docker: Error response from daemon: Network-scoped alias is supported only for containers in user defined networks.

[rade]

needs to strip the net-alias

That gives us no way to recover the aliases on restart. Unless we persist them ourselves.

[bboreham]

Docker has another route to the same feature: docker network connect --alias

[rade]

docker network connect --alias

That is part of #1914.