A few control-center patches

[Bastien Nocera <hadess hadess net>]

Heya,

https://bugzilla.gnome.org/show_bug.cgi?id=645527
The first patch will port the sound panel's theme section to use
GSettings instead of GConf. This piece of code was somehow forgotten in
the process of porting the control-center to GSettings.

https://bugzilla.gnome.org/show_bug.cgi?id=645435
The second patch (the one that adds a new string), moves all the logging
infrastructure to be shared amongst panels. This makes
"gnome-control-center -v" work as expected, and be quiet by default.

Cheers