Automated Tests: How does a user run them?

[hayesall]

Recommendation: Document how tests should be ran (briefly in the README, on a webpage, or in a CONTRIBUTING.md guide).

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pytest seems to pick most of them up:

# Clone
git clone [email protected]:elwinter/nnde.git
cd nnde

# Install and run
pip install pytest
pytest

[elwinter]

README.md was modified to illustrate running the test code with "python setup.py test" and "pytest".