Use fedfind product name (shortname), not 'Fedora'
    
    In the log message and the mail topic we were always using
    'Fedora', so you couldn't easily tell what compose was actually
    being checked (was it a mainline compose or an Atomic nightly?)
    This corrects that.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>