Updated dnsbl to only block exit nodes

This is re: https://8chan.co/meta/res/42025.html

It's unnecessary to block Tor relays, as they only route traffic within the Tor network. Its a minor inconvenience for relay operators, as we have to bypass the DNSBL daily even though we don't use Tor clients. Instead, I suggest you only block exit nodes, as in this pull request.

Note - I haven't tested this at all, I'm just going off http://www.sectoor.de/tor.php