add cache-control header in api response

Author: csoni111

src/fs/service.go

@@ -165,6 +165,7 @@ func directory(fi os.FileInfo, js string, w http.ResponseWriter, request *http.R
 		w.Header().Set("Content-Length", strconv.FormatInt(size, 10))
 		w.Header().Set("Last-Modified", fi.ModTime().UTC().Format(http.TimeFormat))
 		w.Header().Set("Content-Type", "application/json")
+		w.Header().Set("Cache-Control", "max-age=0, private, must-revalidate")
 		w.WriteHeader(http.StatusOK)
 		w.Write(json)
 		status = 200
@@ -266,6 +267,7 @@ func (service *MercuryFsService) serve_file(writer http.ResponseWriter, request
 	} else {
 		writer.Header().Set("Last-Modified", mtime)
 		writer.Header().Set("ETag", etag)
+		writer.Header().Set("Cache-Control", "max-age=0, private, must-revalidate")
 		debug(4, "Etag sent: %s", etag)
 		http.ServeContent(writer, request, full_path, fi.ModTime(), osFile)
 		log("\"GET %s\" %d %d \"%s\"", query, 200, fi.Size(), ua)