Fixed importing Foods with QuantityValue

Fixed double flash when not followed by request
Added Food#destroy error reporting
Simplified prepare_meals with no ingredients
Renamed scope on item with subitems: subitems -> with_subitems

app/views/foods/destroy.js.erb

@@ -1,3 +1,5 @@
 <% if @food.destroyed? %>
   $('tr[id=food-<%= @food.id %>]').nextUntil('tr.primary').addBack().remove();
+<% else %>
+  $('#content').prepend('<%= j error_messages_for @food %>');
 <% end %>