Filter datasets and tasks by user, add user ID to the datasets and tasks

Some of the listing function, for example list_flows allow to pass an uploader ID to only retrieve flows created by a user. Others like list_tasks do not allow that. For example the URL

https://test.openml.org/api/v1/xml/task/list/uploader/68

returns

<oml:error>
<oml:code>480</oml:code>
<oml:message>Illegal filter specified</oml:message>
<oml:additional_information>Legal filter operators: type,tag,data_tag,status,limit,offset,task_id,data_id,data_name,number_instances,number_features,number_classes,number_missing_values. Found illegal filter(s): uploader</oml:additional_information>
</oml:error>

It would be great if the option to filter by uploader was added. Also, I would appreciate if the uploader ID was added to the list for the datasets and tasks.