Fix startup code

[afuechsel]

Improvement for the starter code:

1. use docker-compose to ease the development, made the API URL configurable. Locally running docker-compose uses port 3000/3001, whilst Kubernetes is using 30000/30001.
2. FIxed the Swagger doc for POST requests to allow specification of the payload. Also fixed the documentation of response codes.

[afuechsel]

@SudKul Please have a look on my PR. I think, it's now much better.

Docker compose can be used for the ease of development and swagger models are correctly documents. POST endpoints can now be used in swagger as they document their request payload properly.

The things I couldn't fix, due to my limited python knowledge are:

• use @responds(schema=ConnectionSchema, api=api, many=True) for the connection endpoint is not working (swagger displays an error when opening the model)
• create POST endpoints to accept lists of persons or locations

[afuechsel]

@SudKul the PR is open long since, my project based on the improvements here has been accepted long ago, so why is the MR still open and not merged?