[1.3.X] Fixed #17028 - Changed diveintopython.org -> diveintopython.net

Backport of r17115 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.3.X@17116 bcc190cf-cafb-0310-a4f2-bffc1f526a37