Fixed #17597 -- Marked a word for translation in the comments app's form...

Fixed #17597 -- Marked a word for translation in the comments app's form class. Thanks, Claude Paroz.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17438 bcc190cf-cafb-0310-a4f2-bffc1f526a37