Merge pull request #14 from mazgi/lang/ja

Translated to Japanese, "quickstart" and "architecture".
edit 'what's the difference between' in faq.txt
edit faq.txt
indentation change
require email for olark
Add article links to each available languages
TOC supports i18n
Fix prefix to handle nil properly
Add 'Add other language' section
Add missing articles to ja
Fix generate link of category.erb
Updated section on developing buffered output plugins