add responsive.css. closes #166.
add untranslated 2.1 docs.
Fixed #288 2.1のMigration.mdを翻訳しました
cherry-pick 3b5c456. refs #336
copy the japanese translation of unchanged docs from 2.0.4 to 2.1.
update the latest version to 2.1.
rename the doc's dir from 2.1 to 2.1.0.
delete 2.1 dir.
Closed #256\
Highlights.mdを翻訳しました
remove dir 2.0.
replace assets.
apply the site design of 2.1 to index.html.
apply the new site design. closes #337
translated タグを追加
ScalaCache.md 翻訳
ScalaContentNegotiation.md 翻訳
fix typo. refs #345
translate get-involved page. closes #341
translate download page. closes #340
Closed #325

ScalaFunctionalTest.md 翻訳