Create initial API keys

[roschaefer]

Problem:
Apparently, valid API keys are a table in the database. I don't know how to seed the database with an API key.

Solution:
You could create a seeder script, so I can docker-compose exec db ./seed.sh and have some API keys in the log output maybe.

[roschaefer]

@matthib ah, there is already an issue for this.

[matboehm]

As mentioned by @roschaefer, the creation of API keys need to be mentioned in the Readme.md - whether they need to be created manually or automatically.