Uninstall fails with Mysql 5.5

When I uninstall the module the process fails because Mysql 5.5 does not support "IF EXISTS" for "DROP FOREIGN KEY". Are you using MariaDB for development?

This is a minor problem. I propose to omit the "IF EXISTS". If you want to be shure you can additionally wrap the SQL statement into a try block and catch the exception.

Thank you for the module btw. - I works great!