Fix TFMA jupyter extensions. (#1131)
Fix TFMA jupyter extensions. (#1131)

* We need to install & enable the extensions system wide; otherwise the relevant
  config changes are stored in /home/jovyan and the changes are lost
  when we mount a PV in /home/jovyan.

* It doesn't look like we need to change the command

jupyter labextension install @jupyter-widgets/jupyterlab-manager

  * It doesn't take a --system flag and it looks like its already installed
    system wide.

jupyter labextension install @jupyter-widgets/jupyterlab-manager && \

* Related to #1130
kubeflow/kubeflow,kubeflow/kubeflow,kubeflow/kubeflow,kubeflow/kubeflow,kubeflow/kubeflow,kubeflow/kubeflow