Add another redis cluster with SSL support for QA runs

[boesing]

Feature Request

Q	A
New Feature	yes
BC Break	no

Summary

With #85, we allow SSL context options to be passed to the redis cluster. However, the current implementation of the integration testing does not support SSL as the redis service running the cluster does not support SSL to be enabled.
We use https://github.com/vishnudxb/docker-redis-cluster for integration tests, so that might need patch where SSL could be enabled. I do not have time for this right now and thus won't give it a shot, but maybe some1 else might want to have that.
IMHO its worth to have SSL support properly integration tested here so that our users can trust that we know everything is working when configuring stuff.