Entropy PackageKit backend developers' TODO:

    - add support for FILTER_NOT_VISIBLE, FILTER_NOT_DEVELOPMENT,
        FILTER_DEVELOPMENT, FILTER_VISIBLE
    - implement security filter (Client.get_security_updates())
    - repo_set_data
    - bind get_distro_upgrades to branch hop?
    - sys-apps/entropy is a syspkg
    - messages? how push output to stdout?
    - license dialog??