Expose ability to list networks available to docker containers.
Former user commented on 2017-05-24T17:51:21.000-0400:
sdc-docker commit fc652db (branch master, by Todd Whiteman)
DOCKER-725#icft=DOCKER-725 support `docker network ls`
Reviewed by: Cody Peter Mello <cody.mello@joyent.com>
Approved by: Orlando Vazquez <orlando@joyent.com>