Use tox to run tests on Travis

tox-travis helps make the configuration simple, running all of the tests
for a particular python version on the Travis matrix version of Python.

Add tests of Python 3.3, and drop Python 3.4 from testing with Django
1.6, since it does not support that version of Python.

.gitignore

@@ -5,3 +5,5 @@
 build
 dist
 README.rst
+/.eggs/
+/.tox/

.travis.yml

@@ -1,15 +1,8 @@
+sudo: false
 language: python
 python:
  - "2.7"
+ - "3.3"
  - "3.4"
-env:
- - DJANGO="django==1.6.11" DJANGO_SETTINGS_MODULE="tests.settings"
- - DJANGO="django==1.6.11" DJANGO_SETTINGS_MODULE="tests.swap_settings"
- - DJANGO="django==1.7.7"  DJANGO_SETTINGS_MODULE="tests.settings"
- - DJANGO="django==1.7.7"  DJANGO_SETTINGS_MODULE="tests.swap_settings"
- - DJANGO="django==1.8"    DJANGO_SETTINGS_MODULE="tests.settings"
- - DJANGO="django==1.8"    DJANGO_SETTINGS_MODULE="tests.swap_settings"
-install:
- - pip install $DJANGO
-script:
- - python setup.py test
+install: pip install tox-travis
+script: tox

tox.ini

@@ -0,0 +1,19 @@
+[tox]
+envlist =
+    py{27,33}-django16-{noswap,swap},
+    py{27,33,34}-django{17,18}-{noswap,swap}
+
+[tox:travis]
+2.7 = py27-django{16,17,18}-{noswap,swap}
+3.3 = py33-django{17,18}-{noswap,swap}
+3.4 = py34-django{17,18}-{noswap,swap}
+
+[testenv]
+commands = python setup.py test
+deps =
+    django16: django>=1.6
+    django17: django>=1.7
+    django18: django>=1.8
+setenv =
+    noswap: DJANGO_SETTINGS_MODULE=tests.settings
+    swap: DJANGO_SETTINGS_MODULE=tests.swap_settings