Dependency updates for tox, add typing for Python 2.6 and remove it for 3.5, because that version includes it natively.

tox.ini

@@ -16,6 +16,7 @@ commands =
     py.test []
 [testenv:py26]
 deps =
+    typing
     unittest2
     {[testenv]deps}
 [testenv:py27]
@@ -33,7 +34,6 @@ deps =
     {[testenv]deps}
 [testenv:py35]
 deps =
-    typing
     {[testenv]deps}
 [testenv:cov]
 deps =