related to #1316 method cache size added, data fetched from php not js

Real data need to be created now

ws.php

@@ -128,6 +128,15 @@ function ws_addDefaultMethods( $arr )
       array('admin_only'=>true)
     );
 
+  $service->addMethod(
+      'pwg.getCacheSize',
+      'ws_getCacheSize',
+      null,
+      'Returns general informations.',
+      $ws_functions_root . 'pwg.php',
+      array('admin_only'=>true)
+    );
+
   $service->addMethod(
     'pwg.activity.getList',
     'ws_getActivityList',