Update downloads page (en)

With release of Ruby 2.2, list 2.0.0 as "old" branch and also keep 1.9.3.
Update svn branch names
Keep 2.0.0 mentioned on ruby-core page (en)
Translate Ruby 2.2.0 release post (zh_tw).
Add translation of ruby-2-2-0-released (ja)
Translate 2014-12-25-ruby-2-2-0-released.md (bg)
Fix ruby-2-2-0-released translation (ja)

* Consolidate the translation of "gabage"
* Use "Symbol オブジェクト" instead of "シンボル型オブジェクト"
* Fix mistranslated sentences
* etc.
Merge pull request #934 from makimoto/ruby-2-2-0-released-ja

Add translation of ruby-2-2-0-released (ja)
Rewrap
Merge pull request #935 from gmitrev/news-ruby-2-2-0-bg

Translate 2014-12-25-ruby-2-2-0-released.md (bg)
Fix typos (bg)