tox.ini: Test on Python 3.3 as well as 2.7 and 3.2

I just copied the 3.2 environment for 3.3.  They should be similar,
but it's possible some packages have extra issues on 3.3.

tox.ini

@@ -31,7 +31,7 @@
 
 
 [tox]
-envlist = py27,py32
+envlist = py27,py32,py33
 
 [testenv]
 commands =
@@ -61,3 +61,15 @@ deps =
 #    {distshare}/smartypants-1.6.0.3.zip
 #    {distshare}/typogrify-2.0.0.zip
 #    {distshare}/webassets-0.8.dev.zip
+
+[testenv:py33]
+deps =
+    nose
+    unittest2py3k
+    mock
+    Markdown
+    BeautifulSoup4
+    feedgenerator
+#    {distshare}/smartypants-1.6.0.3.zip
+#    {distshare}/typogrify-2.0.0.zip
+#    {distshare}/webassets-0.8.dev.zip