// Metoda wywoływana po akcji POST, rejestrująca klienta
        [HttpPost]
        public ActionResult RegisterClient(RegisterViewModel registerViewModel)
        {
            try
            {
                if (String.IsNullOrEmpty(registerViewModel.FirstName) ||
                       String.IsNullOrEmpty(registerViewModel.LastName))
                {
                    ViewBag.Message = "Uzupełnij wszystkie pola !";
                    return View("Empty");

                }
                if (ModelState.IsValid)
                {


                    Klient klient = new Klient
                    {
                        Email = registerViewModel.Email,
                        Haslo = registerViewModel.Password,
                        Imie = registerViewModel.FirstName,
                        Nazwisko = registerViewModel.LastName,
                        NrTelefonu = registerViewModel.Phone
                    };
                    CustomerService service = new CustomerService();
                    service.Add(klient);
                    ViewBag.Message = "Sukces";

                }
                else
                {
                    DistrictService service = new DistrictService();
                    registerViewModel.Districts = service.GetDistricts().Select
                     (x => new SelectListItem { Value = x.IdWojewodztwa.ToString(), Text = x.Wojewodztwo })
                     .ToList();
                    registerViewModel.IfBand = false;
                    return View("Register", registerViewModel);
                }
            }
            catch (Exception ex)
            {
                ViewBag.Message = "Istnieje już ten e-mail w bazie";
            }

            return View("Empty");
        }