STYLE: Add SampleData.downloadSample
Created by: jcfr
This is a follow of https://github.com/Slicer/Slicer/pull/1062
Other possible improvement:
- decouple downloading and loading by having
loadFromURL
anddownloadFromURL
- rename
downloadSample
intoloadSample
. Since this may break existing code .. may be we should keep this for Slicer 5.0 ?