empathy: Better separation of concerns between routes and game class

empathy: Better separation of concerns between routes and game class

In this commit we make the route handlers much simpler: Their job is
to parse data from the received request and provide a response to the
client, (such as an appropriate status code), but otherwise, the meat
of the functionality is provided by methods on the Empathy class).

This separation should lead to more maintainable code as the
implementations on both sides are smaller and more focused on a single
job.