Fixes#875
Original showcase images are kept in another directory, and compressed
in webp in the distributed directory.
Since they won't change so much, let's keep them in git.
I've also renamed the templates to *.j2 in order to make things clearer
to others. Having extensions with the name of the locale doesn't seem to
be a good practice, and would need us to add the locales in the MANIFEST
file each time we add one.
Fix#305
* Use absolute imports and rename package to ihatemoney
* Add a ihatemoney command
* Factorize application creation logic
* Refactor the tests
* Update the wsgi.py module with the new create_app() function
* Fix some styling thanks to Flake8.
* Automate Flake8 check in the CI.
