Release script tweaks

The first fix here is to allow `release.sh` to work properly with non-*.docker.io buckets by asking s3cmd for the proper "website" URL (ie, http://bucket.s3-website-REGION.amazonaws.com/, like http://tianon-docker.s3-website-us-west-2.amazonaws.com/).  The second fix is to move our https://get.docker.io/ubuntu/info page directly to https://get.docker.io/ubuntu/ (because we get lots of people hitting that URL and then wondering why it's a 404 and thinking that's why their repo isn't working, when APT doesn't ever even hit that URL), with a URL-backwards-compatibility redirect at /ubuntu/info.  The same fix/tweak was applied for /builds/info to /builds/, for consistency.