fix(systemd): lookup default gateway interface for HOST_IP

- only pull images if they don't already exist in the local docker cache
fix(docker): add docker-patch.service for symlink workaround

In order for data container to function properly, we need
https://github.com/deis/docker/commit/3d9cd1e5f102d5e59011ec4baca2662f3dacbad4

Switching to a fork of docker built from: https://github.com/deis/docker