public function getSignup($code = null)
    {
        if ($code === null) {
            throw new NotFoundHttpException();
        }

        $invite = Invite::where('code', '=', $code)->first();

        if (!$invite || $invite->is_claimed) {
            throw new BadRequestHttpException();
        }

        return View::make('signup')
            ->withCode($invite->code)
            ->withUsername(Binput::old('username'))
            ->withEmail(Binput::old('email', $invite->email));
    }