fix sql query and provide setting to hide online status

mod/ping.php

@@ -50,6 +50,7 @@ function ping_init(&$a) {
 		if($r) {
 			foreach($r as $rr) {
 				q("update chatpresence set cp_last = '%s' where cp_id = %d limit 1",
+					dbesc(datetime_convert()),
 					intval($rr['cp_id'])
 				);
 			}
@@ -67,7 +68,6 @@ function ping_init(&$a) {
 
 	q("delete from chatpresence where cp_last < UTC_TIMESTAMP() - INTERVAL 2 MINUTE"); 
 
-
 	if((! local_user()) || ($result['invalid'])) {
 		echo json_encode($result);
 		killme();