The idea of splitting integration from unittests is good in theory
but leads to a lot of mental overhead. Besides whenever a tests
interacts with a database it isn't a unittest anyway.

Better to use filenames which are commonly used in the python word then
custom ones.

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.