Increase maximum string length of tag aliases

This actually matters now that we have namespaces, and there's no reason
not to bring it up to 255 characters. mysql is going to use 1 size byte
as long as we're below a maximum of 256 characters

gazelle.sql

 
 CREATE TABLE `tag_aliases` (
   `ID` int(10) NOT NULL AUTO_INCREMENT,
-  `BadTag` varchar(30) DEFAULT NULL,
-  `AliasTag` varchar(30) DEFAULT NULL,
+  `BadTag` varchar(255) DEFAULT NULL,
+  `AliasTag` varchar(255) DEFAULT NULL,
   PRIMARY KEY (`ID`),
   KEY `BadTag` (`BadTag`),
   KEY `AliasTag` (`AliasTag`)