Suggested updates

[mpaget]

Some code update suggestions. Capturing here before prioritisation.

1. File: easi-pc-py36/start-notebook.sh
   Suggestion: Contains "install ODC", which could be move out to another script.

2. File: easi-pc-py36/start-singleuser.sh

if [ ! -z "$JUPYTER_ENABLE_LAB" ]; then
  NOTEBOOK_BIN="jupyter labhub"
else
  NOTEBOOK_BIN=jupyterhub-singleuser
fi

Suggestion: Move out to a "start-jupyterhub.sh", perhaps which calls a common "start-common.sh""

3. datacube commands not default path when docker exec -i -t [container] bash
   Suggestion: Add ~/.local/bin to user's path in ~/.bashrc or ~/.profile

[woodcockr]

The start scripting and paths have all been cleaned up.
I'm not moving out install ODC section just yet as it will be fixed by a refactor when aligning to ODC Docker environment as a base now we've sorted out a few things and Docker has a few more tricks up its sleeve.