[WIP] Conversion to new ardmediathek.de website

I tried to convert the addon to use with the new ardmediathek website. The current version is work in progress. Known problems are
* [ ] Categories not working
* [ ] Dossiers not working
* [ ] Next page link on last page is a link to the previous page

Also the addon is not tested really at the moment.

I will try to solve the problems and test my addon-version in the next few days.

ref #7