Graph-based switch-controlplane. Python part.
Graph-based switch-controlplane. Python part.

Note: this CR implements switch-controlplane `with-graph` only partially.
Some code have been reused due to absence of isolation control in
`fuel-cluster-upgrade-extension`.

Change-Id: Icdaec6f57e73b0e4cdec34bf7307e9429af2cb1c

stackforge/fuel-octane,stackforge/fuel-octane