Payment transaction without an atomic commit across 3 partitions

https://github.com/marselester/distributed-payment demonstrates execution of a payment transaction without an atomic commit across 3 partitions (a primer from "Designing Data-Intensive Applications" book). The project uses Kafka to store transfer requests and derived payments. RocksDB is used for requests deduplication (inspired by https://segment.com/blog/exactly-once-delivery/). Repository structure is based on Ben Johnson's https://github.com/benbjohnson/wtf.