Allow listener to be configured for use outside of Heroku

config-sample.json

 {
   "apikey": "",
+  "listener": "0.0.0.0",
   "port": 9001
 }

index.js

@@ -114,6 +114,6 @@ app.post('/post', function(req, res){
 });
 
 //tells Node which port to listen on
-app.listen(app.get('port'), function() {
-  console.log('Weather on the Slash is running on port', app.get('port'));
+app.listen( app.get('port'), config.listener, function() {
+  console.log( 'Weather on the Slash is running on', config.listener, 'and port', app.get('port') );
 });