No way to set max-age = 0 depending on response code - client may cache 404

[IainBapty]

Currently, it's possible for clients to cache 404s because a handle cannot override the max-age. Perhaps either the CachingInterceptor should remove a max-age if the handler has set a response code other than 200 or the handler should be able to set the max-age on a per-request basis.