fix #9091 - rework osm/gpx download tasks - take into account recent changes from OSM server:
- new hashtag scheme
- GPX traces now returned as Bzip2-compressed files

git-svn-id: http://josm.openstreetmap.de/svn/trunk@6244 0c6e7542-c601-0410-84e7-c038aed88b3b