update loggers to use the bool retval of formatError, formatHttpRequest, and formatHttpResponse

[trentm]

Now that formatError, formatHttpRequest, and formatHttpResponse return a bool for whether they processed the field, the loggers should use that to pass through unprocessed fields on the log record. Currently logging a req field that isn't an HTTP request will (a) blow up in v1.0.0, (b) silently drop the "req" field in v1.1.0. I think a future version should log that req field unchanged.