[IMP] account_edi: added error_level + better management of Lock on account.move

- Some errors will never get fixed until user intervention, it doesn't make sense to run the CRON when there is such error.
+ some small improvements and esthetic changes
- When we are in a CRON, we need to commit the changes between each call to web-service to avoid loss of data.
- Small refactor of edi.document prepare_jobs and process_jobs
- Added an arbitrary key to create the batches.