Added another db-testfile for the heatmap
Implement simple aggregator
Fix support for 'dump-all-events-in-the-database'-structure
A new file for filling the database
Clean up `app.js` and `package.json`

* Remove unused `mongodb` dependency.
* Reindent files.
* Remove dead code.
* Format files.
Use dotenv to extract configuration
Update minified_event structure to match frontend
Merge branches 'aggregator' and 'frontend'