Add Italian application.

[dracos]

This PR contains most of #147. The differences are:

• It factors out the find parents code to a shared file between the GB and IT apps.
• Minor flake8 fixes.
• Rebased and squashed with minor commit renames.
• It doesn't include fc0880d (already in master), 2bb188e (now hopefully fixed on master), or bdf7209 (hopefully unnecessary).

[stevenday]

This looks good generally.

I'm not sure if it's possible, but maybe the new FindParentsCommand should raise some kind of error if you haven't set parentmap? You could add a getter method and check for the property or raise NotImplementedError() or something? It seems like something that might trip people up in the future and the error message will be a bit confusing as it stands at the moment.