Default File Manager

GNOME's new Files app (Nautilus) has been a bit controversial. While
the devs have admitted that they should have followed GNOME's feature
proposal process and the UI had some obvious bugs in the 3.5
snapshots, I think Nautilus 3.6 is a clear improvement for most users.

I believe that nautilus 3.8 is the best choice as default file manager
for users and for Ubuntu developers for 13.04. I just don't see
anything else that has the stability, shared maintenance, and
integration with the default desktop that the latest nautilus has.

We should come up with a list of specific requirements that we want
from Nautilus which we can present to developers. Here's my start:

- GtkMenuButton needs to export its menus to dbus for use by the HUD
- While F10 opens the new gear menu, there is no keyboard accessible
way to access the "view menu"
- Traditional keyboard shortcuts like Alt+F, Alt+V, etc. have been
dropped, which I'm thinking could cause trouble for accessibility.