Added missing piece needed for supporting subtitle in Atom feeds.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@5045 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/contrib/syndication/feeds.py

@@ -70,6 +70,7 @@ class Feed(object):
 
         feed = self.feed_type(
             title = self.__get_dynamic_attr('title', obj),
+            subtitle = self.__get_dynamic_attr('subtitle', obj),
             link = link,
             description = self.__get_dynamic_attr('description', obj),
             language = settings.LANGUAGE_CODE.decode(),