Add exclude logging path option

Useful for excluding /ping endpoint to reduce log volume.
This is somewhat more verbose than a simple bool to disable logging of
the `/ping` endpoint.

Perhaps better to add `-silence-ping-logging` bool flag to `options.go` and
pass in the `/ping` endpoint as part of `logger` declaration in `options.go`.

Could be extended into a slice of paths similar to go-gin's `SkipPaths`:
https://github.com/gin-gonic/gin/blob/master/logger.go#L46