Use Horizon project template for django jobs

Horizon defined a project template 'horizon-non-primary-django-jobs'
for django jobs. This patch use that template to run django jobs
here. For information please refer [1]

[1] https://review.opendev.org/#/c/681969/

Change-Id: Id48d23c5cd0fb031ba4c8ce40be900185858d89c

.zuul.yaml

@@ -1,5 +1,6 @@
 - project:
     templates:
+      - horizon-non-primary-django-jobs
       - openstack-python-jobs
       - openstack-python3-train-jobs
       - publish-openstack-docs-pti

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 minversion = 2.0
-envlist = py27,py36,py37,pypy,pep8
+envlist = py27,py36,py37,py3-{dj111,dj22},pypy,pep8
 skipsdist = True
 
 [testenv]
@@ -10,7 +10,10 @@ setenv =
    VIRTUAL_ENV={envdir}
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
-commands = stestr run --slowest {posargs}
+commands =
+   dj111: pip install django>=1.11,<2
+   dj22: pip install django>=2.2,<2.3
+   stestr run --slowest {posargs}
 
 [testenv:pep8]
 basepython = python3