Merge branch 'create-default-serializer' into HEAD

Conflicts:
	lib/active_model/array_serializer.rb

lib/active_model/array_serializer.rb

@@ -31,7 +31,8 @@ module ActiveModel
           serializer = item.active_model_serializer
         end
 
-        serializable = serializer ? serializer.new(item, @options) : item
+        serializable = serializer ? serializer.new(item, @options)
+          : DefaultSerializer.new(item)
 
         if serializable.respond_to?(:serializable_hash)
           serializable.serializable_hash

lib/active_model/serializer.rb

@@ -395,4 +395,20 @@ module ActiveModel
       ActiveSupport::Notifications.instrument(event_name, payload, &block)
     end
   end
+  
+  # DefaultSerializer
+  #
+  # Provides a constant interface for all items, particularly
+  # for ArraySerializer.
+  class DefaultSerializer
+    attr_reader :object, :options
+
+    def initialize(object, options={})
+      @object, @options = object, options
+    end
+
+    def serializable_hash
+      @object.as_json
+    end
+  end
 end