Remove old files before installation

[TrackerSB]

If the version of Green2 changes, the name of the JAR files changes as well. Thus, if old JAR files are not removed prior to copying new ones, conflicts between modules with same name but different JARs may occur.

[TrackerSB]

Due to further investigation the problem resulted from an installation ZIP which contained multiple versions of the same library e.g. Uninstaller[...].jar and ConfigurationDialog[...].jar.