Second part of stock-integration.

Introduced StockArticle and a special page for ordering from stock. StockChanges will be created and the StockArticle.quantity
updated in 'order.close!'.

app/views/deliveries/_stock_change.html.haml

@@ -1,6 +1,9 @@
 %p
   - fields_for "delivery[stock_change_attributes][]", stock_change do |form|
-    = form.select :article_id, articles_for_select(@supplier), :prompt => " -- Artikel auswählen -- "
+    = form.hidden_field :stock_article_id
     Menge
     = form.text_field :quantity, :size => 5, :autocomplete => 'off'
-    = link_to_function "Löschen", "$(this).up('p').remove()"
+    - article = stock_change.stock_article
+    %b= article.name
+    = "(#{number_to_currency(article.price)} / #{article.unit})"
+    //= link_to_function "Löschen", "$(this).up('p').remove()"