Feature Request: Option to skip Public IP for Master nodes of ACS Kubernetes cluster

[vikaskulwal]

Is this a request for help?:
No

Is this a BUG REPORT or FEATURE REQUEST? (choose one):
FEATURE REQUEST

Orchestrator and version (e.g. Kubernetes, DC/OS, Swarm)
Kubernetes

What happened:
We have seen that even if we instantiate ACS within our custom VNet/Subnet, it always assigns a Public IP to master node's i.e its load balancer. And there no option to skip it and have only private IP.

What you expected to happen:
We want an option to have only private IP to master nodes.

How to reproduce it (as minimally and precisely as possible):
Create and ACS kubernetes cluster in private subnet.

Anything else we need to know: