Add percent sign for tax in forms

app/views/stockit/_form.html.haml

@@ -6,7 +6,9 @@
 
   - if stock_article.new_record?
     = f.input :price
-    = f.input :tax
+    = f.input :tax, :wrapper => :append do
+      = f.input_field :tax
+      %span.add-on %
     = f.input :deposit
   - else
     = f.input :price, :input_html => {:disabled => 'disabled'},
@@ -14,4 +16,4 @@
   = f.association :article_category
   .form-actions
     = f.submit class: 'btn'
-    = link_to "oder abbrechen", stock_articles_path
+    = link_to "oder abbrechen", stock_articles_path