Support update from any older version

Incrementally update from other version.
Also, introduce a simpler update script system.

Node configuration file is always called altai-node.json
now. One can continue use master-node.json and
compute-node.json: installer and updater will
decide what file to use and rename it to altai-node.json.

Issue: altai-137
Change-Id: Ic305492735ba86c5e2b6186ecf4820906fa60131