Add a decorator for BlogPosts

Closes refinery#115

app/decorators/controllers/refinery/admin/blogposts_controller_decorator.rb

@@ -0,0 +1,24 @@
+if defined?(Refinery::Blog)
+  Refinery::Blog::Admin::PostsController.class_eval do
+
+    # work around an issue with stack level too deep, due to an issue with decorators.
+    if self.instance_methods.exclude?(:post_params_with_page_image_params)
+      # We need to add :images_attributes to post_params as it is ignored by strong parameters. (See #100)
+      def post_params_with_page_image_params
+
+        # Get the :images_attributes hash from params
+        page_image_params = params.require(:post).permit(images_attributes: [:id, :caption])
+
+        # If there is no :images_attributes hash use a blank hash (so it removes deleted images)
+        page_image_params = {images_attributes:{}} if page_image_params[:images_attributes].nil?
+
+        # Add the :images_attributes hash to the default post_params hash
+        post_params_without_page_image_params.merge(page_image_params)
+
+      end
+
+      # Swap out the default post_params method with our new one
+      alias_method_chain :post_params, :page_image_params
+    end
+  end
+end