apt_key location has changed

The current location is returning a 404

    curl -I http://apt.postgresql.org/pub/repos/apt/ACCC4CF8.asc
    HTTP/1.1 404 Not Found
    Content-Type: text/html
    Content-Length: 345
    Date: Wed, 30 Apr 2014 10:02:00 GMT
    Server: lighttpd/1.4.31

This updates the location per the [README](http://apt.postgresql.org/pub/repos/apt/README)