Reorder dropdown menu for downloadable files

Currently, the dropdown menu on this page admin/store/products/files (the main page that lists downloadable files) has two items listed by default:
1) delete files
2) upload files

This patch rearranges those items:
1) upload files
2) delete files

The reason is that the most common activity on this page is uploading, and the first item in the dropdown is selected by default. Using this patch will save a click (and possibly accidents) for people who are posting a lot of files.