Fixes for dependency issues
    
    Add Recommends: on dnf-command(system-upgrade)
    Fix up Conflicts: on python-dnf-plugins-extras so it actually works
    
    The relevant package in python-dnf-plugins-extras is actually
    python{2,3}-dnf-plugins-extras-common. Comparing against the
    non-existent base package will not result in keeping the plugins
    updated properly.
    
    Signed-off-by: Stephen Gallagher <sgallagh@redhat.com>