first draft for Ruby 2.1.0
update release date
update download links
fixed stable branch
update download links (ja)
fix wrong var
improve correct string
Translate some latest news (pl)
Synchronize footer (pl)
Mention about mruby in downloads (pl)
update md5 and sha1
update announce date
Add security section (pl)
update nurse's comments
Merge pull request #495 from ruby/release-2-1-0

Release announce of Ruby 2.1.0
fix typo
tiny fix
enhancement
Translate 2.1.0 is released (zh_tw).
Merge pull request #502 from JuanitoFatas/2-1-0-released

Translate 2.1.0 is released (zh_tw).