Adopt Helm chart to mimic Amazon EKS CoreDNS naming conventions

I propose to add additional resources to Helm chart to be able to mimic naming conventions of Amazon EKS CoreDNS implementation to quickly move between self-managed CoreDNS, Helm managed CoreDNS and EKS managed ad-on.
Especially the following ressources need name resource

configmap: "coredns"
clusterrole: "system:coredns"
clusterrolebinding": "system:coredns"
service: "kube-dns"

In addition all other resources should allow naming without release name prefix.
I already created a [fork ](https://github.com/youwalther65/helm)of the repo, done all the necessary changes and currently testing it on an Amazon EKS cluster.

Please let me know if a corresponding PR has a chance of being considered.