User requested features

[VoidVolker]

Kraken-io accepting requests for new features in the next node client version. Feel free to ask any additional questions. Main goal in the new version: make code flexible, use new JS features, easy to support and stable. No breaking changes are planned.

• [x] Update client code with modern standards (minimum NodeJS version: 12.20.0)
• [x] Replace deprecated request library to axios and form-data
• [x] Add tests
• [x] Add code documentation
• [x] Use github actions for automatic testing
• [ ] Use github actions for automatic NPM deploy