Include the TF 1.8 image in kubeform_spawner. (#1015)
Include the TF 1.8 image in kubeform_spawner. (#1015)

* There's no reason to upgrade to a more recent Jupyter image because it
looks like the last change to the images was #907 on 06/05.

Fix #1014
kubeflow/kubeflow,kubeflow/kubeflow,kubeflow/kubeflow,kubeflow/kubeflow,kubeflow/kubeflow,kubeflow/kubeflow