refactor: use export global variables instead of express

src/cli.ts

@@ -21,6 +21,7 @@ import {logger} from './common';
  * Get port from environment and store in Express.
  */
 const port = normalizePort(process.env.PORT || '3000');
+// TODO: Can we remove that? It doesn't look like it is read at all.
 app.set('port', port);
 
 /**