Add Moblin Desktop group to comps

[Bill Nottingham]

Peter Robinson (pbrobinson at gmail.com) said: 
> I would like to add a group for the Moblin Desktop. My proposed patch
> is below and feedback is welcome.

... this seems small. There are no other apps required?

You'd want an entry in the desktop category as well. Also, you want to
give the localization team a heads-up, as those strings are translated,
and we've passed string freeze.

Bill