- add ResumptionToken for OAI-ListIdentifiers

- max identifiers and reciords via config
- add constants.php
- add clear-expired command for deleting obsolete cache

app/Constants/constants.php

@@ -0,0 +1,5 @@
+<?php
+
+// Define path to application directory
+defined('APPLICATION_PATH')
+|| define('APPLICATION_PATH', realpath(dirname(dirname(__FILE__))));