Introduce platform-specific adaptation for services used by FreeIPA.
    
    Refactor FreeIPA code to allow abstracting all calls to external processes and
    dependencies on modification of system-wide configuration. A platform provider
    would give its own implementation of those methods and FreeIPA would use it
    based on what's built in packaging process.
    
    https://fedorahosted.org/freeipa/ticket/1605