Prember / Multiple File Support

[Prember](https://github.com/ef4/prember) pre-renders routes into a static directory structure with index.html files at build time. I'd like to be able to use the lightning strategy for deployment and pre-render my static routes. This can be supported by grabbing the files from s3 as assets, but you lose the ability to effectively use revisions, uploading the html as assets using the s3 plugin means the index.html files will be overwritten as they are not fingerprinted. I would like to upload all the html into redis just as it stores the main ember index.html file to retain the ability to have revisions.

I've noticed in the [past a PR](https://github.com/ember-cli-deploy/ember-cli-deploy-redis/pull/80) was rejected, as a use case didn't really exist at the time and the suggestion of using the plugin multiple times as part of the pipeline was the correct advice. The past issues and pr were about uploading a single other file. An app may have tens or hundreds of static routes being prerended by prember so creating a plugin entry for each html file would be cumbersome, prone to error and not very scalable.

I'm creating this issue to spark at the least a discussion about if prembers rising popularity changes the conversation around supporting multiple file support and if it should be pursued as part of this plugin.

まず、プラグインに既存する index.html のアップロードエントリポイントと、却下された ember-cli-deploy-redis の PR #80 を確認し、次に Prember が生成する複数のプリレンダリング済み HTML ファイルを現在のパイプラインに関する助言と比較します。プロジェクトが、リビジョンを保持しながら複数の HTML ファイルを衝突なしで保存するための、合意済みで実装可能なアプローチを持つことが完了の条件です。

索引モデルが issue の本文から書いたものです。