This uses a jail to manage the container's network. Container jails for
all containers in a pod are nested within this and share the network
resources.
There is some code in networking_freebsd.go which is common with
networking_linux.go. Subsequent commits will move the shared code to
networking_common.go to reduce this duplication.
[NO NEW TESTS NEEDED]
Signed-off-by: Doug Rabson <dfr@rabson.org>