OAuth2 Test for Sage access

1. Install ngrok - site: ngrok.com - and register account;
2. Run ./ngrok http 80 from installed folder;
3. Copy https path from terminal console;
4. Create Sage Application endpoint on Sage Developer Site - site: developerselfservice.sageone.com ;
5. Copy Client ID and Client Secret from new app.
6. Update credentials and path (client_id, client_secret, redirect_uri) in index.js.
7. Run Yarn install
8. Run with nodemon index.js