Fixed #3930 usage of split in letsencrypt cron module.

Till Brehm

2016-05-26 0af38c471a32ede3d267742d7652bcd8b9acbe9d

 interface/web/admin/form/server_config.tform.php

@@ -170,7 +170,7 @@
         'formtype' => 'TEXT',
         'default' => '/var/backup',
         'validators' => array(   0 => array (    'type' => 'REGEX',
                              'regex' => "/(|^\\/{1,2}(?:[\\w-]+[.]?\\/?){5,128})$/";
                              'regex' => "/(|^\\/{1,2}(?:[\\w-]+[.]?\\/?){5,128})$/",
                              'errmsg'=> 'backup_dir_error_regex'),
         ),
         'value' => '',