Support using newer versions of babel.

setup.py

@@ -47,7 +47,7 b' requirements = ['
     "pygments>=1.5",
     "whoosh>=2.4.0,<=2.5.7",
     "celery>=2.2.5,<2.3",
-    "babel==0.9.6",
+    "babel>=0.9.6,<=1.3",
     "python-dateutil>=1.5.0,<2.0.0",
     "dulwich>=0.9.3,<=0.9.7",
     "markdown==2.2.1",