Add tox configuration.

Author: joehybird

requirements-dev.txt

@@ -3,3 +3,4 @@ django-nose==1.4.4
 nose==1.3.6
 msgpack-python==0.4.6
 pyyaml==3.11
+tox

tox.ini

@@ -0,0 +1,18 @@
+[tox]
+envlist = py{27}-django{111},py{34,35,36}-django{111,20},py{35,36}-django{21}
+install_command = pip install {opts} {packages}
+
+[testenv]
+basepython =
+    py27: python2.7
+    py34: python3.4
+    py35: python3.5
+    py36: python3.6
+whitelist_externals =
+    make
+passenv =
+    REDIS_CACHE_TEST_SERVER = {env:REDIS_CACHE_TEST_SERVER}
+commands =
+    django111: make test DJANGO_VERSION=">=1.11,<2.0"
+    django20: make test DJANGO_VERSION=">=2.0,<2.1"
+    django21: make test DJANGO_VERSION=">=2.1,<2.2"