Improve Document Conversion
This MR is plan to make cloudooo conversion more reliable(preparation for the next step: remove cloudooo from ERP5 Software release and use public cloudooo)
What is changed in this MR:
- System Preference now accept a list of conversion server
- Add a field in System Preference to define retry count used for network issue case
- Every call to cloudooo now become a loop of tries : retry count x [url1, url2] only in case of network issue