Clean up mysql GRANT being re-run on every puppet run

[jayjanssen]

This happens on every single puppet run:

notice: /Stage[main]/Xinet::Config/Mysql::Rights[clustercheck]/Mysql_grant[clustercheckuser@localhost/mysql]/privileges: privileges changed '' to 'process_priv'

Clean it up!

[jayjanssen]

Tried replacing our current mysql module with the latest: https://github.com/camptocamp/puppet-mysql didn't help the problem.