fixes #1381 orphans calculation is done only when needed by ajax call

ws.php

@@ -593,6 +593,18 @@ function ws_addDefaultMethods( $arr )
       array('admin_only'=>true, 'post_only'=>true)
     );
 
+  $service->addMethod(
+      'pwg.images.calculateOrphansOnAlbumDeletion',
+      'ws_images_calculateOrphansOnAlbumDeletion',
+      array(
+        'category_id' =>  array('type'=>WS_TYPE_ID,
+                                'flags'=>WS_PARAM_FORCE_ARRAY),
+        ),
+      'Return the number of orphan photos if an album is deleted.',
+      $ws_functions_root . 'pwg.php',
+      array('admin_only'=>true)
+    );
+
   $service->addMethod(
       'pwg.categories.getAdminList',
       'ws_categories_getAdminList',