Rewrote tox.ini using new features of tox

tox.ini

@@ -1,44 +1,14 @@
 [tox]
-envlist = django1.4-py26,django1.4-py27,django1.5-py26,django1.5-py27,django1.6-py27,django1.7-py27
+minversion = 1.8
+envlist = django{1.4,1.5}-{py26,py27},django{1.6,1.7}-py27
 
 [testenv]
 deps =
     -r{toxinidir}/test-requirements.txt
+    django1.4: Django>=1.4,<1.5
+    django1.5: Django>=1.5,<1.6
+    django1.6: Django>=1.6,<1.7
+    django1.7: Django>=1.7,<1.8
+
 commands =
     python testproject/manage.py test fiber_test
-
-[testenv:django1.4-py26]
-basepython = python2.6
-deps =
-    Django<1.5
-    {[testenv]deps}
-
-[testenv:django1.4-py27]
-basepython = python2.7
-deps =
-    Django<1.5
-    {[testenv]deps}
-
-[testenv:django1.5-py26]
-basepython = python2.6
-deps =
-    Django<1.6
-    {[testenv]deps}
-
-[testenv:django1.5-py27]
-basepython = python2.7
-deps =
-    Django<1.6
-    {[testenv]deps}
-
-[testenv:django1.6-py27]
-basepython = python2.7
-deps =
-    Django<1.7
-    {[testenv]deps}
-
-[testenv:django1.7-py27]
-basepython = python2.7
-deps =
-    Django<1.8
-    {[testenv]deps}