fixes for authldap

* makes proper use of plugin config
* adds a few first defaults, but the whole config metadata is still
  missing
* proper PHP5 use and comments

lib/plugins/authldap/conf/default.php

+<?php
+
+$conf['port'] = 389;
+
+$conf['groupkey']   = 'cn';
+$conf['userscope']  = 'sub';
+$conf['groupscope'] = 'sub';
\ No newline at end of file