Make it possible to define a custom families folder

Allow to define a custom family folder with a global function from the user-config.py file.
Add try-except structures that prevent issues when you try to use the API from login.py on
a wiki that requires you to first log in to use any part of the API.

Change-Id: I631ecc551900cefb85d45b860dc45e187c0a7395
Merge "Make it possible to define a custom families folder"