Download dbus-java JAR file with all dependencies

Slightly improved version of the Java DBus library provided by freedesktop.org (https://dbus.freedesktop.org/doc/dbus-java/). Changes: - Fixed lot's of Java warnings - Fixed broken 'Gettext' feature (Exceptions on unsupported languages, usage of "_" as method name). - Renamed some classes/methods/variables to comply with Java naming scheme. - Removed usage of proprietary logger and replaced it with sl4fj. - Renamed/refactored some parts to be more 'Java' like (e.g. naming, shadowing) - Fixed problems with DbusConnection.getConnection(SESSION) when using display export (e.g. SSH X11 forward)