Some desktop-links missing

[Nuno Ferreira <nmrf rnl ist utl pt>]

Gnomecal and gtt install in the folder Productivity, gulp and gxsnmp in the
Administration folder.
Both this folders are missing an entry in desktop-links so they can't be
translated (and they don't have the folder icon).
I've made a patch to desktop-links to create this files but I'm not sure if
gnome-core is the right place to put every folder's .directory file?
May I commit this?

-- 
Nuno Ferreira
nmrf@rnl.ist.utl.pt