- Added missing incremental sql file to repository

install/sql/incremental/upd_0057.sql

+CREATE TABLE IF NOT EXISTS `sys_cron` (
+  `name` varchar(50) NOT NULL,
+  `last_run` datetime NULL DEFAULT NULL,
+  `next_run` datetime NULL DEFAULT NULL,
+  `running` tinyint(1) UNSIGNED NOT NULL DEFAULT '0',
+  PRIMARY KEY (`name`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8;