Adding python 3.6 unit test

Adding python 3.6 openstack job to templates, adding py36 to
tox environments and reordering the template jobs.

Change-Id: Ib6269b0d686babfd7973503baa9189efe402e2d8

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 minversion = 2.0
-envlist = py35,py27,pep8,alint,cover
+envlist = py35,py36,py27,pep8,alint,cover
 skipsdist = True
 
 [testenv]

zuul.d/project.yaml

@@ -1,11 +1,13 @@
 ---
 - project:
     templates:
+      - openstack-cover-jobs
+      - openstack-python-jobs
+      - openstack-python35-jobs
+      - openstack-python36-jobs
       - publish-openstack-docs-pti
       - release-notes-jobs-python3
-      - openstack-cover-jobs
+
-      - openstack-python35-jobs
-      - openstack-python-jobs
     check:
       jobs:
         - tenks-tox-ansible-lint