set_collection to be subjectable and stageable

app/controllers/v1/collections_controller.rb

@@ -83,8 +83,8 @@ class V1::CollectionsController < ApplicationController
   def followable; set_collection; end
   def taggable; set_collection; end
   def sociable; set_collection; end
-  def subjectable; set_learning_object; end
-  def stageable; set_learning_object; end
+  def subjectable; set_collection; end
+  def stageable; set_collection; end
 
   def set_collection
     @collection ||= Collection.find(params[:id])