Improve config file management
Improve config file management

- Add a check_manager method.
- Add renaming of a manager_name.
- Replace " by ' for PEP8 reason (not mixing them).

bcornec/python-redfish,uggla/python-redfish,uggla/python-redfish,uggla/python-redfish,bcornec/python-redfish,bcornec/python-redfish