Add Django 2.1 support

Author: jwhitlock

.travis.yml

@@ -36,11 +36,18 @@ matrix:
           python: "3.5"
         - env: TOX_ENV=py36-django20-postgis
           python: "3.6"
+        - env: TOX_ENV=py35-django21-postgis
+          python: "3.5"
+        - env: TOX_ENV=py36-django21-postgis
+          python: "3.6"
         - env: TOX_ENV=py35-django-master-postgis
           python: "3.5"
         - env: TOX_ENV=py36-django-master-postgis
           python: "3.6"
+        - env: TOX_ENV=py37-django-master-postgis
+          python: "3.7"
     allow_failures:
         # Django master is allowed to fail
         - env: TOX_ENV=py35-django-master-postgis
         - env: TOX_ENV=py36-django-master-postgis
+        - env: TOX_ENV=py37-django-master-postgis

setup.py

@@ -86,6 +86,12 @@ def get_long_description():
         "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 :: Apache Software License",
         "Operating System :: OS Independent",

tox.ini

@@ -3,7 +3,8 @@ envlist =
     py{27,34}-django18-{postgis,spatiallite}
     py{27,34,35}-django{19,110}-{postgis,spatiallite}
     py{27,34,35,36}-django111-{postgis,spatiallite}
-    py{35,36}-django{20,-master}-{postgis,spatiallite}
+    py{35,36}-django20-{postgis,spatiallite}
+    py{35,36,37}-django{21,-master}-{postgis,spatiallite}
 
 [flake8]
 exclude = .tox/*,.build/*,.dist/*,build/*
@@ -18,6 +19,7 @@ deps=
     django110: Django>=1.10,<1.11
     django111: Django>=1.11,<2.0
     django20: Django>=2.0,<2.1
+    django21: Django>=2.1,<2.2
     django-master: https://github.com/django/django/archive/master.tar.gz
     postgis: psycopg2
     nose