public ActionResult AddUserAsAdmin(string email)
        {
            var mediator = new AccountMediator();
            mediator.AddUserAsAdmin(email);

            return RedirectToAction("ListUsers", new {message = email+" added"});
        }
        public ActionResult RemoveUser(string email)
        {
            var mediator = new AccountMediator();
            mediator.RemoveUser(email);

            return RedirectToAction("ListUsers", new {message = email+" deleted"});
        }
        public ActionResult ListUsers(string message = null)
        {
            ViewBag.Message = message;

            var mediator = new AccountMediator();

            return View(mediator.ListUsers());
        }