So when I implemented this, I wasn't thinking that we would dump these as kwargs directly to the backend `init`, but I really like that idea. In light of that, I think it can be called `init` and `backend_path` can just be called `path`. Then, I can erase all traces of the fuzzy concept of a `ResourceTrackerBackend`. Want a Resource Tracker that just write json to disk? Just write a new ResourceTracker that implements the yet-to-be-defined interface.