Site.deleteAll ()
function deletes all assets of a site (recursive!)

Sourcecode in Site/objectFunctions.js:
1:   function deleteAll() {
2:      this.images.deleteAll();
3:      this.files.deleteAll();
4:      // FIXME: add deleting of all layouts!
5:      // this.layouts.deleteAll();
6:      this.stories.deleteAll();
7:      this.members.deleteAll();
8:      return true;
9:   }