fixed listShowsAZ to use the correct show link

Navigating to Shows by listShowAZ and then diving into the show episodes did not work any longer.
I fixed the show link calculation. 

However I first started fixing this on XMBC "Gotham" 13.2 and it looks as if a version 3.0.2 of this plugin.video.ardmediathek_de is included there which I could not find in this repository here on Github. 
The changelog here only reaches 3.0.0.

Have you moved the sources somewhere else ?

Cheers, 
Michael (Greifensee)

PS: Deutsch is auch ok ;-)