Install Scripts System Wide

[Christopher Bratusek <nano-master gmx de>]

... I made that feature request a half year ago, so I'm going to try it
again: What about adding  DATADIR/nautilus/scripts as a system-wide
place for installing nautilus-scripts beside
$HOME/.gnome2/nautilus-scripts ? That way we don't have to install the
scripts for each user.

I hope this gets in for 2.24, along with the other new features.

The dusted Bugzilla entry:
http://bugzilla.gnome.org/show_bug.cgi?id=496134