Delete functions should not throw an error, if the ressource does not exists. -> Consider it as deleted if does not exist

- Add env variable GUNICORN_WORKERS (default: 1)
- new Port (8000)
- You don't need to run "flask deploy" by hand anymore

Simplify the deployment process. You don't need to use 'flask db upgrade' or 'flask insert-initial-database-entries' anymore. Instead you just need to use 'flask deploy'.