Update Return codes

Added 127.0.1.6
http://www.spamhaus.org/news/article/713/changes-in-spamhaus-dbl-dnsbl-r
eturn-codes

Removed 127.0.0.8 as it is no longer referenced.
http://www.spamhaus.org/faq/section/DNSBL%20Usage#200
Merge pull request #2 from giovino/master

Update Return codes