Deployed logging no longer has request details

[jwhitlock]

After switching to gunicorn, the logging in stage and production is still in MozLog format, but only has the raw message as the Fields body. Determine how to do detailed logging with gunicorn.

[jwhitlock]

I don't think the existing logging is going to work with gunicorn.

The uvicorn dev logger relies on the additional context, including the request object, that is passed to the logger when run under uvicorn. The uvicorn loggers are much simpler when run as a worker under gunicorn, presumably because gunicorn pre-processes the request.

I think I'll need to return to my original plan (issue #106) to use structlog and have an application-specific logger. In dev, I'll make the uvicorn.access log quiet and emit the application log, and in production the application log will be in MozLog format. This is a bit of rework, but it will more smoothly transition to a logger for background processes.

I'm going to switch to metrics before tackling logs again.