add "delTree" function and add size limit (#2)

conf/config.sample.php

@@ -3,4 +3,5 @@
         define('_HTTP_PROTO','http');
         define('_HTTP_DOMAIN','localhost:8080'); // domain/IP with port if needed
         define('_HTTP_PATH','/');
+        define('_SIZE_LIMIT','2000000'); // in bytes
 ?>