Fix merc attack delay

utils/sql/git/required/2015_01_30_merc_attack_delay.sql

@@ -0,0 +1,3 @@
+ALTER TABLE `merc_stats` ADD `attack_delay` TINYINT(3) UNSIGNED DEFAULT '30' NOT NULL AFTER `attack_speed`;
+UPDATE `merc_stats` SET `attack_delay` = 36 + 36 * (`attack_speed` / 100);
+UPDATE `merc_stats` SET `attack_delay` = 30 WHERE `attack_speed` = 0;