Merge pull request #14 from JasonBoyles/bump-docker-cookbook

Bump docker cookbook revision
allow circle API env overrides
bump chef-client version to 11.16.4
this fixes a bug in the remote_file resource which was causing the docker gpg key
fetch to fail with a 500
Merge pull request #15 from rackspace-orchestration-templates/bump-chef-client

Bump chef client