Added py27 env to tox.ini

Change-Id: I8180ce9d652d9be4be883efb936fcc69532dd498
Related-Bug: #1569334
diff --git a/tox.ini b/tox.ini
index 2f99045..78ea67b 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,6 +1,6 @@
 [tox]
 minversion = 2.0
-envlist = py34-constraints,py27-constraints,pypy-constraints,pep8-constraints
+envlist = py27,py34-constraints,py27-constraints,pypy-constraints,pep8-constraints
 skipsdist = True
 
 [testenv]