public ActionResult Register(RegisterViewModel model)
        {
            if (!ModelState.IsValid)
                return View(model);

            if (Accounts.List.Any(x => x.Username == model.Username))
            {
                ModelState.AddModelError("Username", "Account with a such name already exists");
                return View(model);
            }

            Accounts.Register(model.Username);
            return RedirectToAction("Login", "Account");
        }
 public ActionResult Register()
 {
     var model = new RegisterViewModel();
     return View(model);
 }