Add expiration to query string authorization
Add expiration to query string authorization

Also repair support for query string authorization, regression from
d74a409.

timuralp/s3proxy,andrewgaul/s3proxy,bouncestorage/s3proxy,flandr/s3proxy,kahing/s3proxy,kahing/s3proxy,bouncestorage/s3proxy,andrewgaul/s3proxy,flandr/s3proxy,timuralp/s3proxy