Applet for top downloads

Frogsystem should have an easy way to see which downloads are the most popular downloads on a site.

The code/applet in this pull request takes care of that by listing the top ten downloads in the right nav bar (or wherever the applet is included). These downloads are sorted by the total number of actual downloads for a certain download. For downloads with multiple files, the loads of every file count. E.g. a download with two files of 50 loads each, i.e. 100 in total, will be listed before a single file download with 80 loads.