Prepare nginx proxy config to be installed on controllers

When SSL is enabled nginx is used as SSL termination proxy.
It will be installed on controllers and will proxy requests to
openstack service that listens on localhost.
This patch makes sure nginx site listens only on specific IP, specified
in `nginx_proxy_openstack_api_address` parameter, by default 0.0.0.0
And allow to do flexible configuration of proxy site IP.

Change-Id: I861da305655fd1c8f5b011cef857b7818a00921b
Related-Prod: PROD-16990
4 files changed