https://github.com/op/go-logging has dated a little. to reduce logging overhead we should switch to a zero copy logger like https://github.com/rs/zerolog or https://github.com/uber-go/zap.

Not only will they reduce the number of memory allocations but they will also introduce structured logging, which makes debugging and correlating requests with eg. an elk stack so much more pleasant.

In order to let others inject a logger of their choice we should use a common logger api, see #107