Breaking changes

1. File upload endpoints no longer accept file-like objects. Only byte strings are allowed. This helps prevent errors in previous versions where automatic request retries would use the next part of the stream rather than re-using the portion that was rejected.
2. The return value of the OAuth flows are now an object that includes account_id rather than a tuple. Please use account_id (v2 concept) rather than user_id (v1 concept). This will improve future extensibility.