RCT integration: remote submission

TO integrate PSI-J with RCT, PSI-J would need the ability to submit jobs remotely, usually over an ssh connection.

Still in progress

This does in principle work now as the ZMQ executor exists and works and the REST executor is on it's way. It is not a turnkey solution as the service bootstrapping is missing - that will be covered in #342 and I close this ticket in favor of it.