Allow clients to determine the difference between create or update on PUT

PUT allows an object to be created (http 201).  This allows REST code to
indicate an object has been created and clients to react to it.

APIServer now deals with <-chan RESTResult instead of <-chan runtime.Object,
allowing more data to be passed through.

pkg/client/client_test.go

@@ -57,6 +57,7 @@ type testClient struct {
 	Request  testRequest
 	Response Response
 	Error    bool
+	Created  bool
 	server   *httptest.Server
 	handler  *util.FakeHandler
 	// For query args, an optional function to validate the contents