added CSEP_tests.ipynb

[kirstybayliss]

added test notebook with theory and examples for pycsep tests

[codecov-commenter]

Codecov Report

Merging #173 (dbc4cb0) into master (a521db5) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #173   +/-   ##
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  Coverage   56.09%   56.09%           
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  Files          20       20           
  Lines        3264     3264           
  Branches      519      519           
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  Hits         1831     1831           
  Misses       1314     1314           
  Partials      119      119           

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[mherrmann3]

We should add that this notebook can also be found with much better formatting in /docs/getting_started/theory.rst (#171) - and vice versa: mention in the docs that the contents can be downloaded as Jupyter notebook (https://github.com/SCECcode/pycsep/blob/master/notebooks/CSEP_tests.ipynb).
Alternatively, we could just drop it, but this would remove the opportunity of downloading the notebook and let users play with it.