Upgrade django.

requirements.txt

@@ -1,10 +1,11 @@
-Django==1.5
-django-extensions==1.1.1
+Django==1.6.4
 MySQL-python==1.2.4
 South==0.7.6
 argparse==1.2.1
 distribute==0.6.34
-python-dateutil==1.5
-wsgiref==0.1.2
+django-extensions==1.1.1
 httplib2==0.8
 oauth2==1.5.211
+python-dateutil==1.5
+six==1.6.1
+wsgiref==0.1.2