Merge pull request #11717 from edx/jeskew/django_upgrade_1_8_10

Going head with the bump to Django version 1.8.10 - hopefully, 1.8.11 will show up soon and we'll be able to remove this monkeypatch.

cms/startup.py

@@ -9,7 +9,11 @@ settings.INSTALLED_APPS  # pylint: disable=pointless-statement
 
 from openedx.core.lib.django_startup import autostartup
 import django
-from monkey_patch import third_party_auth, django_db_models_options
+from monkey_patch import (
+    third_party_auth,
+    django_db_models_options,
+    django_utils_http_is_safe_url
+)
 
 import xmodule.x_module
 import cms.lib.xblock.runtime
@@ -23,6 +27,7 @@ def run():
     """
     third_party_auth.patch()
     django_db_models_options.patch()
+    django_utils_http_is_safe_url.patch()
 
     # Comprehensive theming needs to be set up before django startup,
     # because modifying django template paths after startup has no effect.