Merge pull request log4js-node#1 from andyschwarzl/fix-shutdown-error

Pass exit listener name to fix uncaught exception during shutdown.

lib/index.js

@@ -127,7 +127,7 @@ function gelfAppender(layout, config, levels) {
   app.shutdown = function (cb) {
     debug('Shutdown called');
     client.close(cb);
-    process.removeListener(exit);
+    process.removeListener('exit', exit);
   };
 
   return app;