Use edition format for single registration

Previously we were using the Artefact's kind, which would be incorrect when the
artefact was changing kind.
Always use publisher for the owning_app

Previously, if you were to change the owning_app to publisher, it would have
incorrectly retained the old owning_app.
Merge pull request #71 from alphagov/use_correct_kind_in_single_registration

Use edition format for single registration