Register moar formats with panopticon

*This pull request branches from #1258 and should not be merged before it*

Currently, only detailed guides are registered with Panopticon. This pull request changes the service listener to make it register all editions with Panopticon when they're published, regardless of their type.

As other formats have slugs which live under the `/government` prefix, this changes the `RegisterableEdition` class to use the `UrlMaker` to build slugs.