Fix for previously terminated flakes: The last heartbeat sent by the flake will mark the flake as terminated which will make the container cleanup the flake and hence on scale up initialize a new flake.

Fix for failed flakes (where the heartbeat may stop without the terminate flag): Reduce flake-to-container heartbeat duration. Periodic cleanup if heartbeat is not received in time. (will file and fix as a separate issue as part of the fault tolerance feature)

Fixes#12.