    $meanscore = awl->check_address($addr, $originating_ip);
    This method will return the mean score of all messages associated with
    the given address, or undef if the address hasn't been seen before.

    If $originating_ip is supplied, it will be used in the lookup.

    awl->add_score($score);
    This method will add the score to the current entry

    awl->add_known_good_address($addr);
    This method will add a score of -100 to the given address -- effectively
    "bootstrapping" the address as being one that should be whitelisted.

    awl->add_known_bad_address($addr);
    This method will add a score of 100 to the given address -- effectively
    "bootstrapping" the address as being one that should be blacklisted.

