updated mysql adapter to support boolean definition

updated mysql adapter to treat boolean type fields like in rails, it
means that boolean values will be converted to integer(1 for true and 0
for false) values

lib/adapters/mysql.js

@@ -100,6 +100,7 @@ MySQL.prototype.toDatabase = function (prop, val) {
         ].join('-');
         return this.client.escape(val);
     }
+    if (prop.type.name == "Boolean") return val ? 1 : 0;
     return this.client.escape(val.toString());
 };