Added Procfile v1.2

Author: Fabio Beneditto

index.js

@@ -6,6 +6,6 @@ app.get('/', (req, res) => {
   res.send('Hello World!')
 })
 
-app.listen(port, () => {
-  console.log(`Example app listening on port ${port}`)
-})
+app.listen(process.env.PORT || port, '0.0.0.0', () => {
+  console.log("Server is running.");
+});