Tox update

tox.ini

@@ -1,8 +1,16 @@
 [tox]
 envlist = py26,py27,py32
+
 [testenv]
-changedir=demo
-commands=py.test --pyargs pygal []
 deps =
      pytest
      pyquery
+
+[testenv:py26]
+commands=py.test [] {envdir}/lib/python2.6/site-packages/pygal/test
+
+[testenv:py27]
+commands=py.test [] {envdir}/lib/python2.7/site-packages/pygal/test
+
+[testenv:py32]
+commands=py.test [] {envdir}/lib/python3.2/site-packages/pygal/test