placed sql into the data folder as core/module describes

data/sql/playerbots/base/playerbots_rarity_cache.sql

@@ -0,0 +1,7 @@
+DROP TABLE IF EXISTS `playerbots_rarity_cache`;
+CREATE TABLE `playerbots_rarity_cache` (
+  `id` INT(11) auto_increment,
+  `item` INT(11) NOT NULL,
+  `rarity` float NOT NULL,
+  PRIMARY KEY (`id`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8 ROW_FORMAT=FIXED COMMENT='Playerbots Rarity Cache';