ERP5: initial python3 support
This is the initial changes to support running ERP5 on python3
ERP5 changes are tracked in https://lab.nexedi.com/nexedi/erp5/merge_requests/1751
This is the initial changes to support running ERP5 on python3
ERP5 changes are tracked in https://lab.nexedi.com/nexedi/erp5/merge_requests/1751