modemlights: update .ui file
null_applet: remove

- It does not work!. It is added to panel, but will never check for obsolete
  applets, because of incorrect factory id - "NullApplet" set in
  PANEL_APPLET_OUT_PROCESS_FACTORY. It should be "NullAppletFactory".
- With correct factory id applet will be added, but it will show dialog
  every time when panel will be started or restarted. Also there will be
  small 1x1px visual point on panel in place where it was added.
- It is using GConf, but GNOME Panel does not store configuration in gconf
  anymore.
- This applet used to check for BonoboId, but BonoboId is not used anymore.
don't use deprecated gtk_[h/v]box_new