bug 1518653: Update to django-ratelimit 2.0.0
bug 1518653: Update to django-ratelimit 2.0.0

* django-ratelimit 1.1.0 → 2.0.0: Fail open on missing cache, drop
  support for Django 1.10 and earlier, add support for Django 2.0 and
  2.1.

Elchi3/kuma,SphinxKnight/kuma,a2sheppy/kuma,a2sheppy/kuma,Elchi3/kuma,SphinxKnight/kuma,a2sheppy/kuma,SphinxKnight/kuma,mozilla/kuma,SphinxKnight/kuma,SphinxKnight/kuma,mozilla/kuma,Elchi3/kuma,Elchi3/kuma,Elchi3/kuma,mozilla/kuma,a2sheppy/kuma,escattone/kuma,a2sheppy/kuma,escattone/kuma,SphinxKnight/kuma,escattone/kuma,mozilla/kuma,mozilla/kuma