Our test runner code was attempting to look for code in documentation to

run when running the unit test suite. This isn't necessary, and actually

causes problems with Python 3 (it attempts to look up something in

Pipeline's configuration and then exits with an exception). We don't use

doctests, and don't need to spend time looking for them, so turn off

this part of the test run.

Unit tests run on Python 2.7, 3.4, 3.5, and 3.6.