Remove the IdNotFoundError from the project entirely.  ActiveFedora's provided ObjectNotFoundError is more than adequate.  Not sure why I ever implemented the other thing.
Refactor the editable_objects controller to always throw a ParentNotFoundError when that is the problem.
Update core file controller to use the object_404 template.  Leave the other 404 template in just in case it's important.
Add object_404 error to community and collection controller.
Add basic tests for special 404 functionality.
Merge pull request #122 from nu-lts/feature/tombstones

Feature/tombstones