[mysql] clean up plugin variable use and package lists

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
[mysql] limit log collection and add support for MariaDB

Add support for the MariaDB fork of MySQL.

Since a MySQL or MariaDB instance may have very large log files under
/var/log/{mysql,mariadb}. For now restrict log collection to the main
demon log.

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
[mysql] add optional database dump support

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>