Updated default wallpaper for 3.2

[Cosimo Cecchi <cosimoc gnome org>]

Hi,

I just released gnome-themes-standard 3.2.0.1, which contains an updated
default wallpaper by Jakub meant for GNOME 3.2. The release notes use
the new wallpaper extensively already, and the differences with the 3.0
one are really minimal, so I hope this doesn't cause any confusion.

Thanks,
Cosimo