A few small fixes to django.contrib.comments (Comment.get_as_text for...

A few small fixes to django.contrib.comments (Comment.get_as_text for non-authenticated users; references to Comment.permalink; unused imports). Fixes #9143, #9429, and 9439. Thanks, Thejaswi Puthraya.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@9730 bcc190cf-cafb-0310-a4f2-bffc1f526a37