WIP - Fixed the migration, want to make sure the relationships are solid.
WEB-4616 - Okay, we *can* identify KnownUris, now, but don't presently have an automated way to do so, and existing known_uris will all be measurements. Ideally that should depend on some other values...
Okay, I'm calling this ticket done, though only minimally.
WIP - adding relationships between attributes and their accepted values...