Create internal domain for private resources

[bmonkman]

There's a need in some cases to refer to internal resources by user friendly names. For example, kibana and grafana. In this case we should have a private route53 zone with an internal domain where we can create records to point to things that are local to the network, and an ingress controller to be able to route internal traffic to things inside the EKS cluster. The downside of this is that it will be an extra $20/month for another ELB. So maybe we just make it optional?