Remove redundant numbered parameters in str.format() on Python 3.

This was only necessary on Python 2.6.
Merge pull request #483 from berkerpeksag/format-cleanup

Remove redundant numbered parameters in str.format() on Python 3.
Add a simple fixture file for the downloads app.
Merge pull request #484 from berkerpeksag/downloads-fixture

Add a simple fixture file for the downloads app.