Remove NJABL as an example blacklist.

NJABL has been shut down and bopm upstream still lists it in its default
configuration.
---
diff --git a/bopm.conf.sample b/bopm.conf.sample
index 74483e1..bc05bf4 100644
--- a/bopm.conf.sample
+++ b/bopm.conf.sample
@@ -363,18 +363,6 @@ OPM {
 #        };
 
 
-	/* example: NJABL - please read http://www.njabl.org/use.html before
-	 * uncommenting */
-#	 blacklist {
-#	    name = "dnsbl.njabl.org";
-#	    type = "A record reply";
-#	    reply {
-#	       9 = "Open proxy";
-#	    };
-#	    ban_unknown = no;
-#	    kline = "KLINE *@%h :Open proxy found on your host, please visit www.njabl.org/cgi-bin/lookup.cgi?query=%i";
-#	};
-
 	/*
 	 * You can report the insecure proxies you find to a DNSBL also!
 	 * The remaining directives in this section are only needed if you