Configuration files for harmonization methods

[kretep]

In the current CLI, the parameters for the various harmonization methods need to be specified on the command line one-by-one. It would be nice if they could be put in a configuration file (JSON or YML) and the end-user would just pass the path to the configuration file.

Ideally, we would have a schema for each set of parameters (for documentation, validating and perhaps also for GUI-purposes)