Support automatic server-side encryption of Dash props

Enable e.g. dcc.Store to encrypt/decrypt its data-* props on the server, and possibly expand to other components.

#254 was a first cut at implementing this in dash.py and some design discussion is available there. It seems like the way forward here is to make the base component class extensible with server-side transform/inverse_transform extension points.

@chriddyp is there an existing issue that captures other needs/thoughts around the base component extension idea?

まず dash.py の最初の実装と issue #254 の設計に関する議論を読み、次にここで言及されているベースコンポーネントと dcc.Store の data-* props を確認します。サーバー側の transform/inverse_transform アプローチが定義され、dcc.Store の自動的な暗号化と復号が実装され、他のコンポーネントへの拡張範囲が定められた時点で作業は完了です。