Leaving slug generation to documents and manuals puts us in a position where we need objects such as (and I couldn't think of better names) `manual_specific_document_repository_factory` and `validated_manual_document_factory_factory`.

While I'm not usually one to shy away from a good factory factory, I think we could drastically simplify this situation by having slug generation be a concern of our panopticon object.

@evilstreak would you rather address this now or later?