Enable restart services

[norswap]

Right now our python script starts the various services, but if they end, we do not restart them. It would be good if we did, along with a configurable policy for it (how many times to retry, how long between retries).

As of the last PR, we now at least log a warning whenever a service exits unexpectedly. This probably does not really work for blockscout, as this relies on Docker.