Remove the ordereddict backport for Python < 2.7

Fixes #3309 (PARTIAL FIX!!)  The [ordereddict backport](https://pypi.python.org/pypi/ordereddict) in no longer needed because collections.OrderedDict is part of the Standard Library in Python 2.7 and Python 3.  This repo no longer supports Python < 2.7.

requirements.txt

@@ -23,7 +23,7 @@ Markdown==2.6.7
 MarkupSafe==0.23          # via jinja2, mako, webhelpers
 nose==1.3.7               # via pylons
 ofs==0.4.2
-ordereddict==1.1
+# ordereddict==1.1        # Python 2.7+ use stdlib collections.OrderedDict
 Pairtree==0.7.1-T
 passlib==1.6.5
 paste==1.7.5.1