Manual exit should stop running containers

[naorlivne]

Manually exiting the worker-manager should stop running containers, it's important to note that this should only happen if a user manually stops Nebula (ctrl-D) worker-manager and not if the container crash\exits for any reason (even docker stop/kill <container-name>) as on production use the worker-manager is expected to get back online, reconnect to rabbit, pull latest config from mongo & download the image used before rolling the containers in order to minimize impact on the applications containers.