KAZOO-4989 reply error if pickup cookie not found (#96)

kamailio/fast-pickup-role.cfg

@@ -24,6 +24,10 @@ route[FAST_PICKUP_ATTEMPT]
            xlog("L_INFO", "$ci|log|call-id fast pickup call $var(replaced_call_id), redirecting to $du\n");
            route(EXTERNAL_TO_INTERNAL_RELAY);
            exit();
+       } else {
+           xlog("L_INFO", "$ci|log|call-id fast pickup call not found $ru\n");
+           send_reply("404", "Not Found");
+           exit();
        }
     }