Add a network processing scheduler

[Talendar]

Feature:

A processing scheduler (subclass of ProcessingScheduler) capable of assigning work to different machines on a network. The RayProcessingScheduler seems to be able to do that to some extent, but, although I could make it work on a local network, I was unable to use it to split the processing among computers in the Internet.

The network processing scheduler must be able to manage other processing schedulers (workers), each of which is in a different machine.