Detectree2 testing

[ma595]

A quick review of testing in Detectree2 has highlighted the following issues:

• There is a large amount of overlap between the integration test in demo.py and the unit testing in this directory.
• The current testing strategy is to use unittest in coordination with pytest. Is this necessary? Pytest can be used exclusively.
• The unit tests here are not clearly marked as such. Consider moving into unit directory.
• test_models.py will always succeed because of the self.assertEqual(1,1).
• test_evaluation.py is largely incomplete.