Expose v1beta2 API group
Allow server and client to take api version as argument

* Defaults to v1beta1
* apiserver takes -storage_version which controls etcd storage version
  and the version of the client used to connect to other apiservers
* Changed signature of client.New to add version parameter
* All controller code and component code prefers the oldest (most common)
  server version
Merge pull request #1292 from smarterclayton/v1beta2_client

Allow client and server to vary the API versions they use