[#142] Add trace ID into log when tracing is enabled

Signed-off-by: Marina Biryukova <m.biryukova@yadro.com>

api/middleware/reqinfo.go

@@ -34,6 +34,7 @@ type (
 		API          string   // API name -- GetObject PutObject NewMultipartUpload etc.
 		BucketName   string   // Bucket name
 		ObjectName   string   // Object name
+		TraceID      string   // Trace ID
 		URL          *url.URL // Request url
 		tags         []KeyVal // Any additional info not accommodated by above fields
 	}