Log to STDOUT by default, but allow overrides from client code

Presently, all elementary connections log to STDOUT due to the HTTP transport's Faraday configuration. There is no way for client code to configure this.

This isn't great, because in cases where we actually want this data logged, we want control over which logger it goes to. We also want the option to ignore logging data entirely.

The way it's working now is making it hard for us to dig through some of our specs and scaffolding scripts because of how much gets dumped out by Elementary.