- add py37

Change-Id: I151a2351a7fadffd99c843e70c1504135a2c56c6

tox.ini

diff --git a/tox.ini b/tox.ini
index 816d8e6..7a89f0a 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,7 +1,7 @@
 # content of: tox.ini , put in same dir as setup.py
 [tox]
 minversion=1.8.dev1
-envlist = py{26,27,34,35,36}
+envlist = py{26,27,34,35,36,37}
 
 [testenv]
 cov_args=--cov=mako --cov-report term --cov-report xml