On FreeBSD, each container has its own devfs instance with a ruleset
that controls what the container can see. To expose devices to a
container we add rules to its devfs to make the requested devices
visible. For privileged containers, we use 'ruleset=0' which makes
everything visible.
This shares the ParseDevice function with Linux so it moves to
config_common.go from config_linux.go.
Signed-off-by: Doug Rabson <dfr@rabson.org>
