When an S3 client issues a GET request with range specified, Minio
server returns some partial data with 206 http code. The latter
is sent in MINIO_HTTP_TRACE output which is incorrect. This PR
fixes the issue.
When MINIO_TRACE_DIR is provided, create a new log file and store all
HTTP requests + responses data, body are excluded to reduce memory
consumption. MINIO_HTTP_TRACE=1 enables logging. Use non mem
consuming http req/resp recorders, the maximum is about 32k per request.
This logs to STDOUT, body logging is disabled for PutObject PutObjectPart
GetObject.
