Sync libraries page with English version (it)
Merge pull request #413 from mtylty/updated-library-page-update-it

Sync libraries page with English version (it)
Fix that long strings in code can break the layout - resolves #414
zh-CN home download button text change.
Add Mirror site: ruby.taobao.org, add Mirror site for zh-CN;
Merge pull request #415 from huacnlee/fix_download

Fix download
Sync documentation page with English version (it)
Merge pull request #417 from mtylty/updated-documentation-page-update-it

Sync documentation page with English version (it)