Add protobuf preparation objects, guarded by proto tag

pkg/api/unversioned/time.go

@@ -26,8 +26,10 @@ import (
 // Time is a wrapper around time.Time which supports correct
 // marshaling to YAML and JSON.  Wrappers are provided for many
 // of the factory methods that the time package offers.
+//
+// +protobuf.options.marshal=false
 type Time struct {
-	time.Time
+	time.Time `protobuf:"Timestamp,1,req,name=time"`
 }
 
 // NewTime returns a wrapped instance of the provided time