Experiment API is inconsistent with the remaining objects

The current experiment API is inconsistent with the rest of the APIs for other objects.

Here are some remarks:

1. The field declaration on experiments is called configuration.
2. It is not apparently possible to retrieve the field description by looking at the swagger API. Is it?

These changes w.r.t. to the situation before imply that the code in beat.cmdline would have to specialize for experiments. It would be more homogeneous if at least those two items were fixed so that an uniform way to access information for all objects is attainable.

I'm not sure what other implications there are.