Fix sitemap generation and use pyrax to sync to Rackspace

It's good that the other imports from export_database were removed, because it's initially confusing to have anything imported from another module that's in a directory named `scripts`.  I'm not sure if it's worth the trouble to bring in `url_join`, though, or put it someplace else.  Ideally, all common code would be in the `lib` directory instead of the `scripts` directory.