Kubernetes-commit: f78b367db6393a449b8f456e725cbe155d9b90e6
Kubernetes-commit: 79471695c2a16cb7c1fb17adff7765f07e2c9057
This adds a new value transformer to the etcd2 store that can transform the value from etcd on read and write. This will allow the store to implement encryption at rest or otherwise transform the value prior to persistence.