Add to pagure-admin the actions: read-only
    
    This action allows to get or set the read-only status of a project.
    
    With its corresponding unit-tests
    
    Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr></pingou@pingoured.fr>
    
    Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr></pingou@pingoured.fr>