- purge migrations because of splitting log to the extra database
- used new version of generic m2m relation which uses relations without FK
- added multiple database router
- Added DB index to celery log task name.
- Celery log state is field on model now (is not dynamically computed).
- Celery log state is set in LoggedTask with methods on_start_task, on_success_task, on_failure_task and on_retry_task.
- Command set_staletasks_to_error_state was replaced with set_celery_task_log_state command.