Un-compress artifacts after upload
Currently uploading artifacts is really slow if there are lots of files - one way round this is to compress all the individual files into a (e.g.) .tar.gz file, and upload that. Sometimes it is useful to have direct access to the individual files however (e.g. .html files), so this approach doesn't work. If there was a way to un-tar the file after it has been uploaded however this wouldn't be a problem.