Django 2.0 support

Replace django.core.urlresolves with django.urls

(In Django 2.0) The django.core.urlresolvers module is removed
in favor of its new location, django.urls.
It was deprecated in Django 1.10:
https://docs.djangoproject.com/en/2.0/releases/1.10/#id3

Add py35dj20 job to test Django 2.0 integration.
Also drops older Django unit tests from tox.ini
as horizon dropped Django <=1.10 support in Rocky.

Change-Id: I099c7b019c930307d3aae64b1729d6f532fc1653

.zuul.yaml

@@ -4,8 +4,14 @@
         - openstack-tox-lower-constraints:
             required-projects:
               - openstack/horizon
+        - horizon-openstack-tox-py35dj20:
+            required-projects:
+              openstack/horizon
     gate:
       jobs:
         - openstack-tox-lower-constraints:
             required-projects:
               - openstack/horizon
+        - horizon-openstack-tox-py35dj20:
+            required-projects:
+              openstack/horizon

blazar_dashboard/content/hosts/tabs.py

@@ -13,7 +13,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-from django.core.urlresolvers import reverse
+from django.urls import reverse
 from django.utils.translation import ugettext_lazy as _
 from horizon import exceptions
 from horizon import tabs

blazar_dashboard/content/hosts/tests.py

@@ -10,7 +10,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-from django.core.urlresolvers import reverse
+from django.urls import reverse
 import mock
 from openstack_dashboard import api
 

blazar_dashboard/content/hosts/views.py

@@ -10,7 +10,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-from django.core.urlresolvers import reverse_lazy
+from django.urls import reverse_lazy
 from django.utils.translation import ugettext_lazy as _
 from horizon import exceptions
 from horizon import forms

blazar_dashboard/content/leases/tabs.py

@@ -13,7 +13,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-from django.core.urlresolvers import reverse
+from django.urls import reverse
 from django.utils.translation import ugettext_lazy as _
 from horizon import exceptions
 from horizon import tabs

blazar_dashboard/content/leases/tests.py

@@ -12,7 +12,7 @@
 
 from datetime import datetime
 
-from django.core.urlresolvers import reverse
+from django.urls import reverse
 import mock
 import pytz
 

blazar_dashboard/content/leases/views.py

@@ -13,8 +13,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-from django.core.urlresolvers import reverse
-from django.core.urlresolvers import reverse_lazy
+from django.urls import reverse
+from django.urls import reverse_lazy
 from django.utils.translation import ugettext_lazy as _
 from horizon import exceptions
 from horizon import forms

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py35,py27,py27dj18,pep8
+envlist = py35,py27,pep8
 minversion = 2.0
 skipsdist = True
 
@@ -30,29 +30,11 @@ commands =
   coverage xml --omit '.tox/cover/*' -o 'cover/coverage.xml'
   coverage html --omit '.tox/cover/*' -d 'cover/htmlcov'
 
-[testenv:py27dj18]
-basepython = python2.7
+[testenv:py35dj20]
+basepython = python3.5
 commands =
-    pip install django>=1.8,<1.9
-    python manage.py test {posargs} --settings=blazar_dashboard.test.settings
-
-[testenv:py27dj19]
-basepython = python2.7
-commands =
-    pip install django>=1.9,<1.10
-    python manage.py test {posargs} --settings=blazar_dashboard.test.settings
-
-[testenv:py27dj110]
-basepython = python2.7
-commands =
-    pip install django>=1.10,<1.11
-    python manage.py test {posargs} --settings=blazar_dashboard.test.settings
-
-[testenv:py27dj111]
-basepython = python2.7
-commands =
-    pip install django>=1.11,<2.0
-    python manage.py test {posargs} --settings=blazar_dashboard.test.settings
+  pip install django>=2.0,<2.1
+  python manage.py test {posargs} --settings=blazar_dashboard.test.settings
 
 [testenv:eslint]
 whitelist_externals = npm