Remove defaults for security related settings

[tpazderka]

Some classes have security related settings as optional arguments with defined value or do define such value if None is provided. This is considered as a bad practice and either they should not be optional where it makes sense or should raise ImproperlyConfiugured if user tries to use them without providing a value.

[decentral1se]

Sounds sensible!

[schlenk]

At least:

• utils/sdb.py SessionDB password and secret and seed

I don't think examples should matter in this case, if the secrets are in the configuration part.