My fix in 5f23648 forgot to change the receiver registration in the app
config.
Also removed an unused import, and a deprecation warning in the tests.

PR #1447 was by a first-time committer, so I did not want to rewrite
the commits.

* Removed accidentally committed file
* Style fixes

Closes #1447.

This commit is the squashed, but unchanged version of #1447. It adds an
__eq__ method to prices to be able to check them for equality.