change controller_path back to controller_name

This is causing missing constant errors for people who are upgrading

app/controllers/impressionist_controller.rb

@@ -78,7 +78,7 @@ module ImpressionistController
     # creates a statment hash that contains default values for creating an impression.
     def direct_create_statement(query_params={})
       query_params.reverse_merge!(
-        :impressionable_type => controller_path.singularize.camelize,
+        :impressionable_type => controller_name.singularize.camelize,
         :impressionable_id=> params[:id]
         )
       associative_create_statement(query_params)