Add max-age/s-maxage on CC: private/no-cache responses

Varnish does not respect Cache-Control: private or no-cache,
supposedly because "Varnish is not a cache in the RFC2616" sense.
https://www.varnish-cache.org/trac/ticket/1124

Change-Id: I19167342de721530a1968c20779418a73dd3143d
Merge "Add max-age/s-maxage on CC: private/no-cache responses" into production