...since on selinux (and possibly others) we encounter a "bind:
permission denied" error instead, most likely because weave is
attempting to bind a raw ip socket, which is a restricted operation on
those systems.
Fixes#7
...and docker-ns (though we still leave the script around since it's
handy for debugging), and arping (as I have yet to encounter a
situation where it was required)
Bryan Boreham