Ticket 48147 - Install section for dirsrv@.service template
    
    Bug Description:  The commands systemctl enable dirsrv@inst.service do not
    currently operate. This is because of a missing Install section
    
    Fix Description:  Add the install section to the .service template.
    
    https://fedorahosted.org/389/ticket/48147
    
    Author: wibrown
    
    Review by: mreynolds (thanks!)