Drop Django<1.11 and 2.0, fix tests vs Django 2.2b (#320)

Also added py37, pypy3 to tox, travis

.travis.yml

@@ -7,8 +7,14 @@ python:
 - 3.5
 - 3.6
 - pypy
+- pypy3
 install: pip install tox-travis
 script: tox
+matrix:
+  include:
+    - python: 3.7
+      dist: xenial
+      sudo: required
 deploy:
   provider: pypi
   user: jazzband

setup.py

@@ -34,11 +34,8 @@ setup(
         'Development Status :: 5 - Production/Stable',
         'Environment :: Web Environment',
         'Framework :: Django',
-        'Framework :: Django :: 1.8',
-        'Framework :: Django :: 1.9',
-        'Framework :: Django :: 1.10',
         'Framework :: Django :: 1.11',
-        'Framework :: Django :: 2.0',
+        'Framework :: Django :: 2.1',
         'Intended Audience :: Developers',
         'License :: OSI Approved :: BSD License',
         'Natural Language :: English',
@@ -50,6 +47,7 @@ setup(
         'Programming Language :: Python :: 3.4',
         'Programming Language :: Python :: 3.5',
         'Programming Language :: Python :: 3.6',
+        'Programming Language :: Python :: 3.7',
         'Programming Language :: Python :: Implementation :: CPython',
         'Programming Language :: Python :: Implementation :: PyPy',
         'Topic :: Utilities',

tests/settings.py

@@ -7,7 +7,7 @@ from decimal import Decimal
 
 SECRET_KEY = 'cheese'
 
-MIDDLEWARE_CLASSES = (
+MIDDLEWARE = (
     'django.contrib.sessions.middleware.SessionMiddleware',
     'django.middleware.common.CommonMiddleware',
     'django.middleware.csrf.CsrfViewMiddleware',

tests/test_app.py

@@ -6,6 +6,8 @@ from django.test import TestCase, override_settings
 
 
 class TestApp(TestCase):
+    databases = ["default", "secondary"]
+
     def setUp(self):
         self.app_config = apps.get_app_config('constance')
 

tox.ini

@@ -1,12 +1,9 @@
 [tox]
 envlist =
-    py{27,33,34,35,py}-django-18
-    py{27,34,35,py}-django-19
-    py{27,34,35,py}-django-110
-    py{27,34,35,36,py}-django-111
-    py{34,35,36}-django-20
-    py{35,36,37}-django-21
-    py{35,36}-django-master
+    py{27,34,35,36,37,py,py3}-django-111
+    py{35,36,37,py3}-django-21
+    py{37}-django-22
+    py{37}-django-master
 
 [testenv]
 deps =
@@ -14,12 +11,10 @@ deps =
     coverage
     mock
     django-picklefield
-    django-18: Django>=1.8,<1.9
-    django-19: Django>=1.9,<1.10
-    django-110: Django>=1.10,<1.11
     django-111: Django>=1.11,<2.0
     django-20: Django>=2.0,<2.1
     django-21: Django>=2.1,<2.2
+    django-22: Django>=2.2b1,<2.3
     django-master: https://github.com/django/django/archive/master.tar.gz
 usedevelop = True
 ignore_outcome =