Run pep8 as part of default tox run

Change-Id: I516f96bcd07cdff118429e77325059b193ba2690
diff --git a/tox.ini b/tox.ini
index 3163c7d..f183956 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,6 +1,6 @@
 [tox]
 minversion = 2.0
-envlist = py35,py27,flake8
+envlist = py35,py27,pep8
 skipsdist = True
 
 [testenv]