ncm-mysql: option for support of other mysql servicenames

option `servicename` added, which make other servicenames possible, and disables `chkconfig` for EL7
I don't know... it depends if `CAF::Service` now has the capability to implement the permanent modification of the service status. I think that in Madrid we agreed that this was desirable but I am not sure this is implemented yet. Why do you want to remove it? I really think that this should be the responsibility of the component to do it rather than having a template using `ncm-chkconfig` in parallel.