[UIFe] Update Xubuntu wallpaper for Quantal

This bug was fixed in the package xubuntu-default-settings - 12.10.5

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xubuntu-default-settings (12.10.5) quantal; urgency=low

  * etc/xdg/xdg-xubuntu/menus/xfce-applications.menu: don't exclude package
    managers. lp: #1043151
  * etc/xdg/xdg-xubuntu/lightdm/lightdm-gtk-greeter.conf: update logo
    (lp: #1043176) and background image (lp: #1043170).
  * etc/xdg/xdg-xubuntu/xfce4/xfconf/xfce-perchannel-xml/xfce4-desktop.xml:
    update path to wallpaper. lp: #1043170
  * debian/control: bump xubuntu-artwork dep to >= 12.10.1~ for the new wp.
  * etc/xdg/xdg-xubuntu/xfce4/panel/default.xml: drop thunar-tpa and include
    catfish in the bottom panel.
 -- Lionel Le Folgoc <email address hidden> Wed, 29 Aug 2012 19:41:42 +0200

This bug was fixed in the package xubuntu-artwork - 12.10.1

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xubuntu-artwork (12.10.1) quantal; urgency=low

  * Include new wallpaper. lp: #1043170
  * Import elementary-xfce master to fix missing icons. lp: #1006416
  * debian/xubuntu-artwork.install, usr/share/lightdm-gtk-greeter: drop the
    icons, unneeded now.
  * usr/share/pixmaps/xubuntu-lightdm-computer.png: added, for use by
    lightdm-gtk-greeter. lp: #1043176
 -- Lionel Le Folgoc <email address hidden> Wed, 29 Aug 2012 19:52:37 +0200

The wallpaper should be changed on Ubiquity installer too.

Please make a merge proposal for ubiquity:

$ bzr branch lp:ubiquity

The file that needs changing is: bin/ubiquity-dm

We try a few wallpaper names. Or if possible you can add a command to start & use xfconf-query to get the path for the default wallpaper, then no changes will be needed in ubiquity in the future, only to the xubuntu-default-settings.

Dotless wallpaper attached for LightDM and Plymouth, since they don't handle scaling well.

Changes needed (UIFe):
 * Use dotless wallpaper in LightDM
 * Use dotless wallpaper in Plymouth
 * Use new wallpaper in only-ubiquity

Ack - go ahead.

Changes uploaded, no need for an ubiquity task.