Fixed #17194 -- Made sure the auth form tests work if a language other than...

Fixed #17194 -- Made sure the auth form tests work if a language other than English is activated by moving the error message translation strings into class level dictionaries. Many thanks to Claude Paroz, rabio and Bas Peschier for their initial work on this.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17204 bcc190cf-cafb-0310-a4f2-bffc1f526a37