Demo issues

[markNZed]

Thanks for this library. It has been a while since I tried to use node etc and I struggled to understand the demo. It might help others if the amplitudeApiKey is removed, I removed the logger from the expressEndpoint so I could see output on the console, I need to add this code to app.js

const bodyParser = require('body-parser');
app.use(bodyParser.json());

a brief explanation in the README.md as to where to run a server like node http-server and what to expect on the console would help too.