Feature Request - Less verbose mode

[diist]

buildkite-metrics has very verbose logs. In our stacks we're running it every 5 minutes, which turns into 30k log lines a day per instance (and we retain it all).

It would be great to have a -quiet flag that would only print one line in case of success. Or this be default behavior and a -verbose flag to print all the details.

As a workaround, I thought of redirecting stdout to /dev/null but it doesn't work because the standard Go logger sends everything to stderr, see https://golang.org/pkg/log/#pkg-overview .