async function getLocationsUser(req, res) {
    const locations = await gladys.location.get(req.params.user_selector, req.query.from, req.query.to);
    res.json(locations);
  }
@api {get} /api/v1/user/:user_selector/location get user locations
@apiName getLocationsUser
@apiGroup Location
@apiParam {string} [from="1 week ago"] - Start date
@apiParam {string} [to="now"] - End date
@apiSuccessExample {json} Success-Response
[
 {
  "id": "336a8517-b4af-4abe-8b03-28934d6fcf90",
  "user_id": "e4e3f03e-60b9-485e-bc0a-c582b69089bd",
  "latitude": 48,
  "longitude": 12,
  "altitude": 0,
  "accuracy": 20,
  "created_at": "2019-05-09T02:40:36.723Z",
  "updated_at": "2019-05-09T02:40:36.723Z"
 }
]