Fix support for arte.tv

* Videos are now hosted on arte.tv/guide; for new videos, there's a
  redirection from videos.arte.tv to arte.tv/guide

* For a given video, all stream datas are now provided by a JSON file
  instead of a XML file as before

* In this JSON data file, an ID (versionProg) describes the language of
  each available stream:

    versionProg == 1 -> default language version, matching the video URL
                        language

    versionProg == 2 -> alternate language version

    versionProg == 3 -> original version with default language subtitles

    versionProg == 8 -> default language version with subtitle for
                        hard-of-hearing

* I took the liberty of adding the stream protocol to the generated
  stream ID, to distinguish same-quality videos (some videos are
  available through HTTP, in addition of RTMP, for some MD/LD videos,
  probably for mobile phones

* The tests were updated to reflect these changes

Signed-off-by: Mohamed El Morabity <melmorabity@fedoraproject.org>
Reviewed-by: Toni Gundogdu <legatvs@gmail.com>
media/arte.lua: Use the 'a?b:c' -idiom

Signed-off-by: Toni Gundogdu <legatvs@gmail.com>
media/arte.lua: Arte.to_id: Return ID in lowercase

Signed-off-by: Toni Gundogdu <legatvs@gmail.com>