Updated Sprints and Tasks pages on wiki

[Owen Taylor <otaylor redhat com>]

I went through today and updated:

 http://live.gnome.org/OnlineDesktop/Sprints

  Stripped this down to be purely what people are working on currently;
  I moved all the future stuff to work on to "Tasks", and deleted all
  the completed tasks, which I don't think were that useful.

 http://live.gnome.org/OnlineDesktop/Tasks
  
  Grouped into sections, and added a bunch more items. My idea is that
  we should keep this page pretty simple and if we want to expand in
  detail on any idea, we should create a separate wiki page and link
  to it from Tasks.

- Owen