Code drop including:
Code drop July 28th from f3ee8433304fadca8c22d0a46db2ea4326b2ee8d
It includes major changes regarding bulk data writing:
- Enh: add new attributes into Opencensus request's trace: x-user-id, x-app-id and content-length
- Feature: Enable worker to write bulk data with session, the data conflicts management is also included.