WIP: Finn/async

Description

This is a really rough idea to use async messages to send an operation status back to the client. It uses the library Janus:

https://github.com/aio-libs/janus

This WIP MR is purely to show a rough draft of what it could look like.

Changes proposed in this merge request:

• Threadsafe updating of queue in the Scheduler (to be renamed to something like JobRegister)
• Clients now wait on the get() method
• Does this actually buy us much or should I just keep a standard Threadsafe Queue?
• Any other ideas?