use new-style tox.ini, add flake8-docstrings, add docstrings

tests/test_factory.py

@@ -24,6 +24,7 @@ def test_title_override():
 
 
 def test_media_file_access(client):
+    """Test that media files are served, and properly."""
     response = client.get('/media/favicon.png')
     assert response.status_code == 200
     assert response.headers['content-type'] == 'image/png'