This PR adds a new service account for kubestack. It also
- creates essential cluster role for the service account
- generate kubernetes config based on the service account secrets
- add KUBERNETES_SERVICE_HOST and KUBERNETES_SERVICE_PORT env varibles
Change-Id: I33679efba982f23dd32c9e5632b3e16580f177ea
Signed-off-by: Pengfei Ni <feiskyer@gmail.com>