public JsonResult CreateUser(User user)
        {
            List<User> lst = Session["users"] as List<User>;

            user.id = lst.Count+1;
            lst.Add(user);

            return Json(user);
        }
        public JsonResult UpdateUser(int id, User user)
        {
            List<User> lst = Session["users"] as List<User>;
            User us = lst.First(u => u.id == id);
            us.name = user.name;
            us.email = user.email;

            return Json(user);
        }