Move back to the old version of download.sh
Move back to the old version of download.sh

The choice of the branch to download the data provoqued to many
problems. The original solution with one data set to download is much
better.

wkrzemien/j-pet-framework,JPETTomography/j-pet-framework,alexkernphysiker/j-pet-framework,wkrzemien/j-pet-framework,wkrzemien/j-pet-framework,alexkernphysiker/j-pet-framework,alexkernphysiker/j-pet-framework,wkrzemien/j-pet-framework,JPETTomography/j-pet-framework,wkrzemien/j-pet-framework,alexkernphysiker/j-pet-framework,JPETTomography/j-pet-framework,alexkernphysiker/j-pet-framework