Add service_manage paramters

Hi,

When you make HA with corosync/pacemaker for exemple, the mysql service
status should be managed by corosync/pacemaker. 

This PR add a service_manage new parameter allowing yourself to specify whatever you want puppet to managed mysql services or not.

Default value is, of course, true.

I think such feature could be usefull in other module (like apache,tomcat and any other which can be used in HA mode).

Regards