Workaround pull request #41 of biomaj project. We try to mimic files stored in cache.dir during update of a bank.

- Due to the way 'save_session' set 'last_update_time' field in db, we set it again with the value found in MySQL database to the right value.

Keep history of bank during migration (on/off)

Tested against biomaj 3.0.13

- Reformatted code following pep8 (ignored E501 (line too long))
- Added new option -H/--keep_history allowing not to store only the production data from
  a bank, but also the releases history. Thus, it is almost a complete migration of bank
  history life.
- Now storing the logfile (from biomaj1.2.x) into the session field.

New MySQL connector for python 2 and 3

Updates to get right production info

Set correct session id from production creation date
Avoid duplicate session while migrating again