ref(Vagrantfile): align with upstream coreos-vagrant

See "deis" fork at https://github.com/deis/coreos-vagrant
Merge pull request #1881 from mboersma/update-coreos-vagrant

ref(Vagrantfile): align with upstream coreos-vagrant
ref(tests): move test-nightly to test-latest
Merge pull request #1965 from gabrtv/test-latest

ref(tests): move test-nightly to test-latest
ref(builder): use ubuntu:14.04 as Dockerfile base image
ref(cache): use ubuntu:14.04 as Dockerfile base image
ref(controller): use ubuntu:14.04 as Dockerfile base image
ref(database): use ubuntu:14.04 as Dockerfile base image
ref(database): update postgres user uid/gid in confd templates
ref(logger): use ubuntu:14.04 as Dockerfile base image
ref(registry): use ubuntu:14.04 as Dockerfile base image
ref(router): use ubuntu:14.04 as Dockerfile base image
ref(tests): use ubuntu:14.04 as Dockerfile base image
chore(pip): update pip installs to 1.5.6
ref(data): use ubuntu:14.04 as Dockerfile base image