Don't show icon if icon_url is blank

app/views/layers/show.html.haml

@@ -42,7 +42,7 @@
       %td= link_to 'Delete', s, :confirm => "Delete #{s.feed.title}?", :method => :delete, :class => "button"
       %td= link_to 'Edit icon', edit_subscription_path(s), :class => "button"
       %td
-        - unless s.icon_url.nil?
+        - unless s.icon_url.blank?
           = image_tag s.icon_url
         - else