api/v1beta1: use go-dockerclient instead of docker-api-structs

This involves updating go-dockerclient and removing the patched code.

Related to #692 and fsouza/go-dockerclient#146.
Merge pull request #1194 from fsouza/remove-godockerclient-copiedstructs

api/v1beta1: use go-dockerclient instead of docker-api-structs