Move all order logic to models

- Have a default order for each model
-- The overall default is ID DESC
- Allow for custom orderings
-- When comma-separated IDs are used

app/controllers/dmails_controller.rb

@@ -20,7 +20,7 @@ class DmailsController < ApplicationController
       cookies.permanent[:dmail_folder] = params[:folder]
     end
     @query = Dmail.active.visible.search(params[:search])
-    @dmails = @query.order("dmails.created_at desc").paginate(params[:page], :limit => params[:limit])
+    @dmails = @query.paginate(params[:page], :limit => params[:limit])
     respond_with(@dmails) do |format|
       format.xml do
         render :xml => @dmails.to_xml(:root => "dmails")