VirtualBox Guest Additions fully working

This was the work required to get things working with shared folders to the guest.  

Dbus was added to stop virtualbox guest service from bouncing. Virtualbox uses dbus to communicate.  Everything was patchelf-ed to include dbus.  mount.vboxsf was added back to the nix expression.  not sure why it went missing.  it's required to issue a mount -t vboxsf command successfully.