Add stock_article_selection (deleting multiple stock articles at once)

app/controllers/stockit_controller.rb

@@ -3,6 +3,7 @@ class StockitController < ApplicationController
   def index
     @stock_articles = StockArticle.includes(:supplier, :article_category).
         order('suppliers.name, article_categories.name, articles.name')
+    @stock_article_selection = StockArticleSelection.new
   end
 
   def new