Convert to LogbackSteno #2
Description
We should convert all logging inside the project from SLF4J to LogbackSteno. This has become our defacto logging library even in core libraries. The consensus has been that even though LogbackSteno is an implementation and not just an API, it is much richer and safer than the alternative. Perhaps we should consider extracting an API (see ArpNetworking/logback-steno#26).