Implemented #remove_rule method.

extensions/dns/dns.rb

@@ -76,6 +76,18 @@ module BeEF
           end
         end
 
+        # Removes the given DNS rule.
+        #
+        # @param id [String] rule identifier
+        #
+        # @return [Boolean] true if rule was removed, otherwise false
+        def remove_rule(id)
+          @lock.synchronize do
+            rule = BeEF::Core::Models::Dns::Rule.get(id)
+            rule.nil? ? false : rule.destroy
+          end
+        end
+
         # Entry point for processing incoming DNS requests. Attempts to find a matching rule and
         # sends back its associated response.
         #