Added in the HTTP headers to tell proxy severs (and other caches) to disabled caching documents.

header.inc.php.template

@@ -69,6 +69,12 @@
     "config_passwd" => "changeme"
   );
 */
+
+  /* If you do not want phpGroupWare to be cached by proxy servers, uncomment the following */
+  /* This is recommended, but not required. */
+  //header("Cache-Control: no-cache, must-revalidate");  // HTTP/1.1
+  //header("Pragma: no-cache");                          // HTTP/1.0
+
   /**************************************************************************\
   * Do not edit these lines                                                  *
   \**************************************************************************/