More patches for gnome-control-center

[Cosimo Cecchi <cosimoc gnome org>]

Hi,

a new day, a new couple of patches for gnome-control-center. I hope
these are the last patches I ask permissions to break code freeze for
g-c-c.

- https://bugzilla.gnome.org/show_bug.cgi?id=646180
Draw the background preview at the requested size instead of scaling up
the 128x128 thumbnail we get from GnomeBG. This makes a huge difference
in the background panel.
- https://bugzilla.gnome.org/show_bug.cgi?id=646183
Make the XKB options dialog in "Region & Language" modal. It's confusing
for it not to be modal, as you could end up having the dialog not
following the selected keyboard layout, or even have more than one
dialog open at the same time, and this also makes it consistent with
similar dialogs in other CC panels.

Thanks,

Cosimo