Sorting of submissions by default

When you watch the webform results (node/%webform_menu/webform-results), you can see that newest submissions appear at the bottom of the page. The early results appear at the top of the page. This is not usability, because every time you watch results, you have to change their order. Especially if you have a big list of submissions.

In this regard I propose change order by default.
Here's the patch.