use json to encode user list

apps/files/ajax/scan.php

@@ -9,7 +9,7 @@ if (isset($_GET['users'])) {
 	if ($_GET['users'] === 'all') {
 		$users = OC_User::getUsers();
 	} else {
-		$users = explode(',', $_GET['users']);
+		$users = json_decode($_GET['users']);
 	}
 } else {
 	$users = array(OC_User::getUser());

apps/files/js/files.js

@@ -711,7 +711,7 @@ function scanFiles(force, dir, users){
 		if (users === 'all') {
 			usersString = users;
 		} else {
-			usersString = users.join(',');
+			usersString = JSON.stringify(users);
 		}
 		scannerEventSource = new OC.EventSource(OC.filePath('files','ajax','scan.php'),{force: force,dir: dir, users: usersString});
 	} else {