Skip sending optional parameters on POST request when unspecified

[lbalmaceda]

Changes

The python request library when it creates the query parameters, it will remove any parameter on the passed dict that has a value of None. In our library, these are only used for GET requests.
For the case of POST or PATCH requests, the dict that conforms the body will not suffer the same filtering.

In some cases it makes sense to send an explicit null value, like when removing a property from the user's user_metadata property, the check should be performed on each POST/PATCH function instead of in the base client class.

The PR also includes some linting fixes, related to doc blocks and formatting.

References

Fixes #228

Docs on the params filtering https://requests.readthedocs.io/en/master/user/quickstart/#passing-parameters-in-urls. Note it doesn't explicitly mention how the body params are being handled.

Testing

Please describe how this can be tested by reviewers. Be specific about anything not tested and reasons why. If this library has unit and/or integration testing, tests should be added for new functionality and existing tests should complete without errors.

• This change adds unit test coverage
• This change adds integration test coverage
• This change has been tested on the latest version of the platform/language or why not

Checklist

• I have read the Auth0 general contribution guidelines
• I have read the Auth0 Code of Conduct
• All existing and new tests complete without errors