Revert "Revert "Add an api object for the kubelet, and a versioned endpoint.""

This reverts commit dcfcf315e5943caf1ccc1779e3a6b83beb48fc35.
Fix the kubelet uses api encode/decode by actually adding PodContainerInfo to v1beta1
Merge pull request #2942 from brendandburns/kubelet

revert the revert along with fixes to make it pass e2e tests.