v3.1.0 - support naming objstorage cofigurations - add statsd probes - replace the ObjStorageFilter scaffolding by a true ObjStorage proxy - rename ReadOnlyObjStorage and NonIterableObjStorage exceptions as ReadOnlyObjStorageError and NonIterableObjStorageError - make the ReadOnlyObjStorageProxy raise a HTTPReadOnlyObjStorage instead of silently no nothing on mutating endpoints.