Fixed #3287: method columns in the admin changelist can now have a {{{boolean}}} attribute that uses the clever little checkmark icons instead of the ugly "True" or "False" strings.  Thanks for the patch, xian@mintchaos.com

git-svn-id: http://code.djangoproject.com/svn/django/trunk@4309 bcc190cf-cafb-0310-a4f2-bffc1f526a37