Add `stat/device-basic` endpoint

[sgrodzicki]

Adding missing (lightweight) endpoint for basic device information. Useful for filtering on type or other basic fields. Example output:

{
    "meta": {
        "rc": "ok"
    },
    "data": [
        {
            "mac": "d0:21:f9:fa:5f:38",
            "state": 1,
            "adopted": true,
            "disabled": false,
            "type": "uap",
            "model": "U6M",
            "in_gateway_mode": false,
            "name": "AP Lab"
        },
        {
            "mac": "b4:fb:e4:d2:17:8c",
            "state": 2,
            "adopted": false,
            "disabled": false,
            "type": "usw",
            "model": "US8P60",
            "in_gateway_mode": false
        }
    ]
}

[malle-pietje]

Thanks, looks like a nice and useful endpoint for specific use-cases! Will merge asap.