v0.9.0
- storage*: Drop intermediary conversion step into OriginVisit
- pg: use 'on conflict do nothing' strategy for duplicate metadata rows.
- Make the code location of metadata endpoints consistent across backends.
- Add content_metadata_{add,get}.
- Add context columns to object_metadata table and object_metadata_{add,get}.
- Generalize origin_metadata to allow support for other object types in the future.
- Work around the segmentation faults caused by pytest-coverage + multiprocessing.