Upgrade gevent to 1.0.1

Upgrade to a post-1.0 version of gevent so we can avoid strange DNS behavior in the 'monkey-patched' httplib2 library.

NOTE: this also makes the FQDN used for "metadata.google.internal" consistent with the way its specified in other tooling (e.g. gcloud, gcutil, gsutil, gcs boto plugin, java's ComputeCredential)
This was done by @jbeda in https://github.com/GoogleCloudPlatform/docker-registry/pull/9/files#r14172398 on purpose, I would leave it that way.