Our unit tests have been using the Python-Markdown version to determine

what results to expect when rendering. We were using an outdated

variable for this version, and that variable was just removed in this

week's Python-Markdown release.
This change updates our unit tests to check the modern variable. This is

compatible with all supported versions of Python-Markdown.

Unit tests pass for Python 2.7 and 3 with the latest Python-Markdown on

each.