Remove download_url from setup.py

* Prevents issues with moving download locations in the future, see
  https://www.djangoproject.com/m/bad-installer.txt
* Removes a location that release managers need to update with a
  new version
* Very little use when files are hosted on PyPI (as Django's are)

setup.py

@@ -93,7 +93,6 @@ setup(
     author = 'Django Software Foundation',
     author_email = 'foundation@djangoproject.com',
     description = 'A high-level Python Web framework that encourages rapid development and clean, pragmatic design.',
-    download_url = 'https://www.djangoproject.com/m/releases/1.5/Django-1.5.1.tar.gz',
     license = "BSD",
     packages = packages,
     cmdclass = cmdclasses,