New string to translate - field_text. It appear when you trying save empty wiki-page. See #6448 for reference.
Translation updates
* ja (#6441)
* ru
* zh-TW (#6451)


git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@4169 e93f8b46-1217-0410-a6f0-8f06a7374b81