Fixed #5909 -- Made the various django.contrib.comment models more robust in

the face of non-ASCII characters by giving them a __unicode__ method and
letting the default __repr__ use that. Patches from prairiedogg and scompt.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@6742 bcc190cf-cafb-0310-a4f2-bffc1f526a37