fix google#1607; use container creation time provided by Docker handler

Author: sentinelt

container/docker/handler.go

@@ -391,6 +391,7 @@ func (self *dockerContainerHandler) GetSpec() (info.ContainerSpec, error) {
 	}
 	spec.Envs = self.envs
 	spec.Image = self.image
+	spec.CreationTime = self.creationTime
 
 	return spec, err
 }