func CachableResponseWriter(req *http.Request,
	statusCode int,
	resp http.ResponseWriter,
	opts Options) ([]cacheobject.Reason, time.Time, error) {
	return cacheobject.UsingRequestResponse(req, statusCode, resp.Header(), opts.PrivateCache)
}
Given an HTTP Request, the future Status Code, and an ResponseWriter,
determine the possible reasons a response SHOULD NOT be cached.
package cachecontrol
import (
	"github.com/pquerna/cachecontrol/cacheobject"
	"net/http"
	"time"
)
type Options struct {
	PrivateCache bool
}