Endomondo integration: fixed

Sportablet 8.3 and the Uploader for Garmin 7.3 can upload to Endomondo again. Fixing this thing took some time because Endomondo does not support third parties, and when they do massive changes on their website, I have to follow their new flow and update the code accordingly. That's why I declared this integration to be a "permanent beta" from the very beginning.

Thanks for your patience guys.