Get docker deb from GCS.

Also lock to 1.3.0 due to issues in 1.3.1 (docker/docker#8889)
Merge pull request #2104 from jbeda/gcs-docker-install

Get docker deb from GCS
Fix a missing lock in the fake etcd client.
Merge pull request #2108 from brendandburns/fix

Fix a missing lock in the fake etcd client.