Still didn't have incoming-do-todo logic right

* gnorb-gnus.el (gnorb-gnus-incoming-do-todo): Make sure nil value
  propagates correctly.
Remove gnus-interactive

* gnorb-gnus.el (gnorb-gnus-incoming-do-todo gnorb-gnus-view): Don't use
  gnus-interactive, it may not work quite right in earlier versions of
  Gnus.