Adopt to generally accepted argument conventions (Python, JSON, CLI)

[DunklesArchipel]

          We might want to adopt camel case in our JSON files.

According to the getting started section from frictionless

Arguments conform to the following naming convention:
- for Python interfaces, they are snake_cased, e.g. `missing_values`
- within dictionaries or JSON objects, they are camelCased, e.g. `missingValues`
- in the command line, they use dashes, e.g. `--missing-values`

Originally posted by @DunklesArchipel in #76 (comment)