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 but there is no unit-test added in vitrage-dashboard to check 
django compatibility as of now and maybe we can add them in future.
For information please refer [1]

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

Change-Id: I6fd838618048f7cd373e477d176e9ad2ee8e3f09

.zuul.yaml

@@ -24,6 +24,7 @@
 - project:
     templates:
       - horizon-nodejs10-jobs-nonvoting
+      - horizon-non-primary-django-jobs
       - openstack-python-jobs-horizon
       - openstack-python3-train-jobs
       - publish-openstack-docs-pti

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 minversion = 2.3.2
-envlist = py27,py37,pep8,npm
+envlist = py37,py36,py3-{dj111,dj22},pep8,npm
 skipsdist = True
 
 [testenv]
@@ -13,7 +13,10 @@ deps =
    -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
    -r{toxinidir}/test-requirements.txt
    -r{toxinidir}/requirements.txt
-commands = {envpython} {toxinidir}/manage.py test vitrage_dashboard {posargs} --exclude-tag integration {posargs}
+commands =
+   dj111: pip install django>=1.11,<2
+   dj22: pip install django>=2.2,<2.3
+   {envpython} {toxinidir}/manage.py test vitrage_dashboard {posargs} --exclude-tag integration {posargs}
 
 [testenv:integration]
 # Run integration tests only