[appletrailers] Rework extraction (fixes #1387)

The exraction was broken:
* The includes page contains img elements that need to be fixed.
* Use the 'itunes.inc' page, it contains a json dictionary for each trailer with information.
* Get the formats from 'includes/settings{trailer_name}.json'
* Use urljoin to allow urls with a fragment identifier to work

Removed the thumbnail urls from the tests, they are different now.