Fix ranking refresh

When changing the rank of a story the rank got changed in Rally but we
did not update the data in the current view. Therefore, if another rank
update request was made that involved the same story then it was not
properly updated. The fix was to update the model and view with the
stories new rank.
Refresh backlog when story is deleted

After deleting a story from the backlog the view did not refresh so
even though the story was removed from Rally it still appeared to be
there. This fix updates the view to remove the deleted story.