Prepare to support python3.6

This patch prepares python3.6 support.

We should add py36-local into tox.ini and support for python3.6
into setup.cfg when we decide to support python3.6 formally.

Change-Id: Ief38d75d7ccea880a7424f18a607bb4c8032568c

.zuul.yaml

@@ -1,6 +1,8 @@
 - project:
     check:
       jobs:
+        - openstack-tox-py36:
+            voting: false
         - nodejs-npm-run-lint:
             vars:
               node_version: 4

tox.ini

@@ -44,9 +44,6 @@ commands = python setup.py test --coverage --testr-args='{posargs}'
 # NOTE(shu-mutow): On CI infra, horizon will be installed
 # according to job setting. but on local, we need to install
 # horizon from master branch.
-[testenv:py27]
-basepython = python2.7
-
 [testenv:py27-local]
 basepython = python2.7
 commands =
@@ -59,6 +56,12 @@ commands =
   {[testenv:hz-local]commands}
   {[testenv]commands}
 
+[testenv:py36-local]
+basepython = python3.6
+commands =
+  {[testenv:hz-local]commands}
+  {[testenv]commands}
+
 [testenv:py3-dj111]
 basepython = python3
 commands =