Remove as_json item caching

Again I'm just not convinced of the perf on this, and it enables us to delete some whole infra over it, we can improve it another time if it's useful to!

app/controllers/items_controller.rb

@@ -37,9 +37,8 @@ class ItemsController < ApplicationController
         end
       end
     elsif params.has_key?(:ids) && params[:ids].is_a?(Array)
-      @items = Item.build_proxies(params[:ids])
+      @items = Item.find(params[:ids])
       assign_closeted!
-      @items.prepare_method(:as_json)
       respond_to do |format|
         format.json { render json: @items }
       end

app/models/item/update_task.rb

@@ -1,22 +0,0 @@
-class Item
-  class UpdateTask
-    extend FragmentExpiration
-
-    TIMEOUT_IN_SECONDS = 10
-
-    @queue = :item_update
-
-    def self.perform(id)
-      Timeout::timeout(TIMEOUT_IN_SECONDS) do
-        item = Item.find(id)
-        expire_cache_for(item)
-      end
-    end
-    
-    private
-
-    def self.expire_cache_for(item)
-      expire_key_in_all_locales("items/#{item.id}#as_json")
-    end
-  end
-end

app/models/item_observer.rb

@@ -2,11 +2,6 @@ class ItemObserver < ActionController::Caching::Sweeper
   def after_create(item)
     Resque.enqueue(Item::CreateTask, item.id)
   end
-  
-  def after_update(item)
-    # CONSIDER: can pass item.changes.keys in to choose which caches to expire
-    Resque.enqueue(Item::UpdateTask, item.id)
-  end
 
   def after_destroy(item)
     Resque.enqueue(Item::DestroyTask, item.id)