Use Data Classes to Type Objects

[schmidni]

User Story

As a developer I would like to have explicitly typed objects so that it is clearer what happens in my code.

Acceptance Criteria

Since the main job of the software is to push data back and forth, it would be a huge help to use explicit data types. All the communication that currently happens by passing dictionaries should be converted to data classes.

Those data classes can be used for the repositories and webservice