Proof of concept mechanism for hiding questions related to ineligible benefits

From #51:
> Screening seem to be working as intended for the MVP release. Some post-mvp improvements for hiding questions based on benefits 'in play' is recommended. Some questions that are benefit-specific will still appear after a benefit has already been determined ineligible. For example "Have you continuously owned and occupied your property as your primary residence since at least July 1, 2014?" still appears when LOOP has been marked as already enrolled. This question does not pertain to any of the other benefits

この issue では、ファイル、テスト、エントリーポイントが指定されていません。まず screening ロジックと、すでに対象外と判定された benefit がどのように表現されているかを特定してください。LOOP が対象外と判定された後に、LOOP property question のような benefit 固有の質問が表示されなくなり、関連のない質問は引き続き表示されれば完了です。

索引モデルが issue の本文から書いたものです。