Fixed #5816 -- Fixed a regression from [6333] that generates incorrect cookie "expires" dates when using a locale other than English. Introduced `http_date` and `cookie_date` utility functions. Thanks for the report Michael Lemaire. Thanks for the patch Karen Tracey and `SmileyChris`.

      git-svn-id: http://code.djangoproject.com/svn/django/trunk@6634 bcc190cf-cafb-0310-a4f2-bffc1f526a37