Issue with NAS server data

[Previnkumar-G]

Setting parameters allow_unmapped_user, enable_windows_to_unix_username to False , sets it to None instead of False. Please check if this is the appropriate behavior.

To reproduce:-

• Call UnityNasServer.modify with allow_unmapped_user=False and enable_windows_to_unix_username=False
• Get updated data using get_nas_server

Data returned will have values as None instead of False