This bumps aws-sdk-go to the latest version (currently unreleased), to
workaround a Godep problem when a package listed in Godeps no longer
exists on the master branch.  See #16238 for the gory details.

Fixes #16238.

We will likely want to bump up again to the next released version once
it is released, but this version appears to be pretty similar to the
last released version (0.9.16)