Before building JOSM you need to call ant bootstrap to download ivy. Use
bootstrap-workspace task to populate lib/ directory with all libraries
used by project. This is useful when working with IDE. Eclipse project
is migrated to use this files.

Open issues:
- whether ant clean task should also clean ivy cache
- whether include ivy jar in JOSM repository or use bootstrap task and
download it to ant home
- whether to use version in names in lib/ directory
- why some classes in org/apache/commons/jcs/auxiliary/remote/** are
required in runtime
- what to do with kitfox svg and gnu getopt