Start apiserver with additional flags for enabling the aggregator

[tagarwal]

Description of issue:

We need the apiserver of the k8s cluster installed started with these additional parameters

--proxy-client-key-file=/etc/kubernetes/pki/front-proxy-client.key 
--proxy-client-cert-file=/etc/kubernetes/pki/front-proxy-client.crt 
--requestheader-client-ca-file=/etc/kubernetes/pki/front-proxy-ca.crt

This is for the apiserver aggregator to work correctly. https://github.com/kubernetes-incubator/apiserver-builder/blob/master/docs/concepts/aggregation.md#enabling-the-aggregator