Allow creation of StockArticles also if there are no Articles for a supplier in delivery form

app/views/deliveries/_form.html.haml

@@ -106,6 +106,9 @@
     %tfoot
       %tr
         %th{:colspan => 5}
+          - if articles_for_select2(@supplier).empty?
+            = link_to t('.create_stock_article'), new_stock_article_supplier_deliveries_path(@supplier), :remote => true, :class => 'btn'
+          - else
             %input#new_stock_article{:style => 'width: 500px;'}
     %tbody
       - for article in stock_articles_for_table(@supplier)