public ActionResult AddNewBus(int capacity, string license, string state)
        {
            DatabaseInterface db = new DatabaseInterface();
            if (!db.IsLicenseUnique(license))
                return Json("false");

            Bus bus = new Bus()
            {
                Id = ObjectId.GenerateNewId(),
                LicensePlate = license,
                BusId = db.GetNextBusId(),
                Status = BusStatus.Active,
                Capacity = capacity,
                State = state,
                AssignedTo = -1

            };
            db.AddBus(bus);
            return Json(new{
               success = "true",
               id = bus.Id.ToString()
            });
        }