Clean up test infrastructure

Author: jbaiter

tests/conftest.py

@@ -4,7 +4,7 @@
 # and then run "tox" from this directory.
 
 [tox]
-envlist = py27, py33, py34, pypy
+envlist = py27, py34, py36, pypy
 
 [testenv]
 commands = py.test