Changed
- The `update` to use `nested_dict_update` from `typeutils` 2.5+ so
config value updates can be updated safely in a nested way e.g. in
order to have a base config file and then a much smaller override
config file
- The `__str__` and `__repr__` and calls so they now mask out secrets and
passwords _(any keys with the following words in them: 'pass', 'key',
'secret', 'token')_