Integrate builds in openshift origin

Merge of build work into origin repository. Includes API client for origin and k8s.
For the initial POC work, it was easier to have each concrete strategy implementation do the push itself. This is mainly because the resulting built image "artifact" lived either on the host (using the host's Docker socket) or in the dind container. I think ultimately it would be nice to have something like you see with Jenkins, where the build artifacts are made available (and possibly persisted) after the build has completed. This way, the build controller could be responsible for doing the pushing.