Migrate the logcom service to be celery based and triggered
    
    This is another service that we can drop, simplifying both the
    architecture as well as maintenance.
    In addition, it will make python3 support easier since celery supports
    python3 while trollius doesn't and is even deprecated actually.
    
    Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>