feature: In Productionmode the App will now deliver minified scripts and styles

- New Tasks in gruntfil.js to concat and minify the css and js files
- When the node app runs in production mode (NODE_ENV=production nodemon app.js) it will deliver the minified versions of styles.css and scripts.js
- Index.html will now load just 2 files instead of more than 20.
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Closes #20
Procfile changed to start the app on Heroku always in production mode
chore: Set Logger MaxSize to prevent to large logfiles

Closes #23
refactor: some small code reorganizations in app.'s
refactor: Files in api folder renamed to *requestHandler.js

- This is for the clarification for the responsibility of this classes

Closes #24