Break ipaplatform / ipalib import cycle of hell
    
    Here is an attempt to break the import cycle of hell between ipaplatform
    and ipalib. All services now pass an ipalib.api object to
    services.service(). RedHatServices.__init__() still needs to do a local
    import because it initializes its wellknown service dict with service
    instances.
    
    Signed-off-by: Christian Heimes <cheimes@redhat.com>
    Reviewed-By: Martin Basti <mbasti@redhat.com>