Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

 Add configuration item to allow kubeadm join to use a dns name pointing to control plane

This adds a new flag (`--apiserver-advertise-dns-address`) to kubeadm which is used in node kubelet.confg to point to API server allowing users to define a DNS entry instead of an IP address.

Fixes kubernetes/kubeadm#411

```release-note
Adds new flag `--apiserver-advertise-dns-address` which is used in node kubelet.confg to point to API server
```
// @timothysc @craigtracey