Support `--net=container:<container_id>`

[partkyle]

Similar to #1, dns should also resolve for container networking.

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