Refacto of Tiles handling and simplified a bit file naming for tiles/params.
By the way, fixes #297

THIS COMMIT BREAKS FILE LAYOUT AND REQUIRES MIGRATION (SEE BELLOW).

To migrate data :

cd tiles
find . '*.jpg' -exec rename 's/[^\/]*_(([0-9]{3}_){2}([0-9]{3}))/$1/' {} \;...

The one-step upload now handles as well the tiles generation and stops on generation errors if needed

tolerate that the dir exists before tiles creation

moved panorama generation to class : PanoramaGenerator