It's possible to configure log fields in the configuration file, and we would
like these fields to be included in all logs. Previously these fields were
included only in logs produced using the main routine's context, meaning that
any logs from a request handler were missing the fields since those use a
context based on the HTTP request's context.
Add a configurable default logger to the `context` package, and set it when
configuring logging at startup time.
Signed-off-by: Adam Wolfe Gordon <awg@digitalocean.com>
43e502590f