c/r: get rid of dump_net_info()

c/r: get rid of dump_net_info()

This was originally used to propagate the bridge and veth names across
hosts, but now we extract both from the container's config file, and
nothing reads the files that dump_net_info() writes, so let's just get rid
of them.

Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>