Set "Software" metadata field to point to datalad-dataverse and its version

[yarikoptic]

idea: whenever datalad-dataverse first communicates with dataverse dataset or even each time push to dataverse it would be nice if it set/extended metadata "Software" record with version of datalad-dataverse. This would allow for non-ambiguous search for "DataLad" datasets based on software record in metadata instead of ad-hoc file pattern matching envisioned in

• Support discovery of datalad datasets on dataverse datalad-usage-dashboard#46