Merge pull request #139 from hynekcer/master

Fixed broken Preview (displaying the old article content)
pull #139 - form data from args or kwargs
pull #139 - form data from args or kwargs
Merge branch 'master' of github.com:benjaoming/django-wiki
pull #139 - form data from args or kwargs
French translation - changed msg id (att. pull #138)
Fixed RuntimeWarning by replacing naive datetime by utc
Added more tests and refactored the the first one.
Fixed on_article_delete if the article has children.

Reported by tests.py: "variable referenced before assignment"
Added tests for clearing cache and for updating article_list