tox.ini: Add nose and pytest deps

tox.ini

@@ -1,5 +1,10 b''
 [tox]
-envlist = py26, py27
+envlist = py{26,27}-{pytest,nose}
 
 [testenv]
-commands = nosetests
+deps =
+    nose: nose
+    pytest: pytest
+commands =
+    nose: nosetests {posargs}
+    pytest: py.test {posargs}