contentType: Reply back proper contentTypes based on the file extension.

Currently the server would set 'application/octet-stream' for all
objects, set this value based on the file extension transparently.

This is useful in case of minio browser to facilitate displaying
proper icons for the different mime data types.

api-headers.go

@@ -78,7 +78,7 @@ func setObjectHeaders(w http.ResponseWriter, metadata fs.ObjectMetadata, content
 	// set object headers
 	lastModified := metadata.Created.Format(http.TimeFormat)
 	// object related headers
-	w.Header().Set("Content-Type", "application/octet-stream")
+	w.Header().Set("Content-Type", metadata.ContentType)
 	if metadata.Md5 != "" {
 		w.Header().Set("ETag", "\""+metadata.Md5+"\"")
 	}