Adding back in py33 because removing didn't help.

Sean Reifschneider · Sean Reifschneider · commit 288c159720ee · 2016-12-17T19:50:50.000-07:00
diff --git a/tox.ini b/tox.ini
@@ -1,6 +1,6 @@
 [tox]
 minversion = 1.6
-envlist = py27,py34,py35,pypy,pep8
+envlist = py27,py33,py34,py35,pypy,pep8
 skipsdist = True
 
 [testenv]
