Added CacheControl support to Headless Server

Headless Server now supports sending CacheControl headers for GET requests. Defaults can be configured using the caas.cache-control.* properties. The value of the the max-age directive is the minimum of the configured max-age value for the given request URL and the values of the validFrom/validTo properties of the requested contents. If no cache control configuration exists and the content does not contain a value for validFrom/validTo then no CacheControl header is sent. A negative max-age value indicates that no CacheControl header should be sent even in the presence of configured validFrom/validTo dates.

Follow Section, “Added CacheControl support to Headless Server” for upgrade information.

(CMS-19110)