Make _download_store_for_reading() have a single return point; fix order of download store overrides so that Tar downloads would get read from S3 if "read_gridfs_downloads_from_s3" is set to "yes"
Merge branch 'read_gridfs_downloads_from_s3'
Add missing "postgresql" and "amazon_s3" download storage methods
Merge branch 'read_gridfs_downloads_from_s3'
Merge branch 'master' into extractor_training