curl -H "X-Auth-Token: 9HqLlyZOugoStsXCUfD_0YdwnNnunAJF8V47U3QHXSq" \
     -H "X-User-Id: aobEdbYhXfu5hkeqG" \
     -H "Content-type: application/json" \
     http://localhost:3000/api/v1/groups.invite \
     -d '{ "roomId": "ByehQjC44FwMeiLbX", "userId": "nSYqWzZ4GsKTX4dyK" }'

{
  "group": {
    "_id": "ByehQjC44FwMeiLbX",
    "ts": "2016-11-30T21:23:04.737Z",
    "t": "p",
    "name": "testing",
    "usernames": [
      "testing",
      "testing1"
    ],
    "u": {
        "_id": "aobEdbYhXfu5hkeqG",
        "username": "testing1"
    },
    "msgs": 1,
    "_updatedAt": "2016-12-09T12:50:51.575Z",
    "lm": "2016-12-09T12:50:51.555Z"
  },
  "success": true
}