switch unit testing to py.test

[prjemian]

This will match what the bluesky framework is using

[prjemian]

Since pytest can run the existing unit tests, what work remains to close this issue?

[prjemian]

Current unit tests use unittest and pytest. Conversion of all unit tests to only pytest will take some time and seem unnecessary now. Moving to next milestone now.

[prjemian]

(bluesky_2021_2) prjemian@zap:~/.../BCDA-APS/apstools$ git grep unittest | grep import
tests/__main__.py:import unittest
tests/test_apsbss.py:import unittest
tests/test_commandlist.py:import unittest
tests/test_exceltable.py:import unittest
tests/test_plans.py:import unittest
tests/test_simple.py:import unittest

[prjemian]

The entire purpose of __main__.py is to queue the tests for unittest