Drop github.com/docker/engine-api packages

[soltysh]

This is a continuation of #818 and a post-1.8 k8s rebase task.
The problem is that github.com/docker/docker already contains the types from github.com/docker/engine-api, the latter is just an old version of the former. This in the end should clean our vendor dir slightly and eventually lead to a cleaner vendor inside origin, as well.