Support `--net=host`

[partkyle]

--net=host does not return any results.

It should return the DOCKER_HOST port as a default. This could be as simple as adding an option for what to advertise when a container is using host networking.

...
    "HostConfig": {
...
        "NetworkMode": "host",
...
    },
...
    "NetworkSettings": {
        "Bridge": "",
        "Gateway": "",
        "GlobalIPv6Address": "",
        "GlobalIPv6PrefixLen": 0,
        "IPAddress": "",
        "IPPrefixLen": 0,
        "IPv6Gateway": "",
        "LinkLocalIPv6Address": "",
        "LinkLocalIPv6PrefixLen": 0,
        "MacAddress": "",
        "PortMapping": null,
        "Ports": null
    },
...