DFD examples from Threat Model Cookbook

[zbraiterman]

It could be nice to add some examples to the Object Model descriptions wiki page ( https://github.com/izar/pytm/wiki/Object-Model-(sample) ) from the OWASP Threat Modeling Cookbook ( https://github.com/OWASP/threat-model-cookbook/tree/master/Flow%20Diagram ) that use pytm to generate DFDs.