ncm-mysql: option for support of other mysql servicenames

option `servicename` added, which make other servicenames possible, and disables `chkconfig` for EL7
Agreeing with @piojo about SL3/4 and anyway the schema allow to define explicitly the service so it will still possible to get the new component working for them, even though this is completely useless...
With the schema modification that I propose (servicename mandatory), remove this if..else... and just call CAF::Process with servicename.