[Openicc] SANE device color management

[Richard Hughes]

At the moment, gnome-color-manager uses libsane to get the list of
scanner devices, which allows it to calibrate the scanner and also
allows applications like gnome-scan to request the correct color
profile to embed in any scanned documents.

I would like to move the libsane dependency to colord in the next
version of gnome-color-manager, so scanner devices can be autoassigned
in the future like the other device types.

The only hesitation I've got in doing so, is because this would
require using libsane as the colord execution user, currently root.
I'm not sure if using libsane as root is a really bad idea or whether
I'm worrying about nothing. I sure couldn't find anything in google.

Knowledge welcome, thanks.

Richard.