Integrate with Dockerfile based healthchecks

[naorlivne]

Expected/Wanted Behavior

Nebula should integrate with Dockerfile based healthchecks so that if a container is defined as unhealthy it restarts it, it should default to on but have a per app flag that allows disabling that feature

It should be noted that if\when this will become included in the Docker engine it should really be used throughout that, either via Nebula passing Docker engine the needed settings or (hopefully) that becoming Docker engine default and means noting will be needed to be done Nebula side.

Actual Behavior

Currently Nebula\Docker engine only restarts crashed containers & ignores the Docker engine health checks results

[naorlivne]

Pushed to latest, will be added to the next numbered release.

Due to new labels required to get this feature added this required making a semi-breaking change, while no API changed running the latest version while still having dangling work containers of an earlier version will result in a restart loop, the fix is to stop\kill & rm all work containers and let the new nebula version to recreate them.