Proper job typing

[fretchen]

To finish #137 we need to have clean types for the job. What would this actually be ? This object would most certainly be passed in

upload_job, get_job and add_job

[fretchen]

The main challenge remains that each varying number of keys.

So on some level it is a dict with keys

{"experiment_0": ExperimentDict,
...}

If we can type this roughly we are in good shape.

[fretchen]

Given how many tests we are already running in check_json_dict it is really not clear that we need this anymore...