PLAT-1633: Upgrade django-ratelimit-backend to 1.1.1

cms/urls.py

@@ -1,8 +1,7 @@
 from django.conf import settings
 from django.conf.urls import include, patterns, url
 from django.conf.urls.static import static
-# There is a course creators admin table.
-from ratelimitbackend import admin
+from django.contrib import admin
 
 from cms.djangoapps.contentstore.views.organization import OrganizationListView