Fix mailing list subscription form

Re-enables subscription via form by changing
the action url to newly created webservice.
Add missing 'code' class on mailing-lists page (ja)
Announce new ruby-lang.org (en)
:fr translation for the new website annonucement.
Typos (fr)
Many minor fixes; add some conferences (fr)

* typos
* grammar
* s/librairie/bibliothèque/
* french conferences added: RuLu, La Conf, DotRB
Fix typo in link
Fix errors on to-ruby-from pages (perl, C)
Remove broken links from to-ruby-from-perl page