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/pool_versions_controller.rb

@@ -7,7 +7,7 @@ class PoolVersionsController < ApplicationController
       @pool = Pool.find(params[:search][:pool_id])
     end
 
-    @pool_versions = PoolArchive.search(params[:search]).order("updated_at desc").paginate(params[:page], :limit => params[:limit], :search_count => params[:search])
+    @pool_versions = PoolArchive.search(params[:search]).paginate(params[:page], :limit => params[:limit], :search_count => params[:search])
     respond_with(@pool_versions) do |format|
       format.xml do
         render :xml => @pool_versions.to_xml(:root => "pool-versions")