See https://golang.org/s/go15vendor
This commit moves the google.golang.org/cloud/... packages. The rest
of third_party will move later.
This commit is a dependency for some cloud logging work which we'll
develop in Camlistore's tree.
Also, delete my old gce package from third_party and only use the
google metadata package (which my gce package became, and which was
also already vendored into third_party)
Fixes#596
Change-Id: I64fd6f1e9dc6f433466f91f81efd2ecbf039334f
Brad Fitzpatrick