'timezone' configuration for mysql needed

[Yang Youseok]

Timezone is very common config to be modified in mysql, so I think it's better to be maintained in Trove.

I wonder how to add new configuration variable, so anyone who can help me little bit hints would be appreciated. I willing to add by myself.

'https://wiki.openstack.org/wiki/Trove/Configurations/mysql-options' mentions some variable like 'character_set_filesystem' would be configurable but I could not find any related sources. Now, I guess the variables which are mentioned above will just be validated by validatotion-rules.json and real my.cnf having the config should be added at /etc/my.cnf.d/ by operator manually.

Thanks.