public User Register(RegisterUserCommand command)
        {
            var user = new User(command.Email, command.Password, command.IsAdmin);
            user.Register();

            _repository.Register(user);

            if (Commit())
                return user;

            return null;
        }
        public Task<HttpResponseMessage> Post([FromBody]dynamic body)
        {
            var command = new RegisterUserCommand(
                email: (string)body.email,
                password: (string)body.password,
                isAdmin: (bool)body.isAdmin
            );

            var user = _service.Register(command);

            return CreateResponse(HttpStatusCode.Created, user);
        }