[ynet] Remove test md5sums

These fluctuate regularly.
[youtube:playlist] Fix test title
[xtube] Fix test description
[vine:user] Adapt test to changed list size
[vimeo:review] Fix test title
[vgtv] Simplify
[vgtv] Fix test title
[ustream:channel] Change test playlist size (Seems to have been limited that way on the website as well)
[syfy] Remove test checksum

We have the minsize test now.
[ruhd] Simplify
[pornhub] Modernize and fix test definition
[test_download] Improve error message
[Makefile] remove temporary files in clean target
[gorillavid] Fix test title
[generic] Fix test title
[francetv] Remove changing md5sum
[promptfile] Fix check for deleted videos
[nbc] Fix ThePlatform embedded videos
[kickstarter] Simplify and fix test case
[heise] Fix extraction

Now they use an XML format instead of JSON.