ustreamIE
credit @jaimeMF
typo
Revert "In tests.json file and md5 join in a 'files' list to handle multiple-file IEs"

This made the JSON structure really unreadable and was a quick fix.

This reverts commit 6535e9511fc18eee2fc640c77fd42a4a39791915.
Adapt test_download to support playlists, and remove race conditions
Simplify test parameter initialization