data: disable DroneBL lookups by default (#147)

Closes #109

This was a hack I did on stream. I thought this would have a positive
effect, but a combination of real-world testing from people using Anubis
in prod and gray-hat testing has proven this is an unfeature and is
probably causing more harm than good at this stage.

In the future I'll probably make the `dnsbl` block more flexible so that
you can specify your own lists and rules around them.

Signed-off-by: Xe Iaso <me@xeiaso.net>

data/botPolicies.json

@@ -394,5 +394,5 @@
       "action": "CHALLENGE"
     }
   ],
-  "dnsbl": true
-}
+  "dnsbl": false
+}