Download service now pipes to both curdling & install

Now the download service notifies both curdling and install. To be able
to do that, a couple things were changed;

 * The `Service.queue` signature has changed to:
   >>> queue(package, sender_name, **data)

 * Both Curdling and Installer now raise the `NotForMe` exception when
   they receive a package they don't know how to deal with
New release: 0.1.4