Finalize enu hardware architecture

Since we have decided to get rid of PC104 and use a moxa for serial devices, enuActor(s) can be run on any machine which is on the PFS network.

There are several options, but a choice has to be made at some point.

We can run 4 enuActor instances on one machine :

• either on a dedicated server/RasPI
• an existing pfs server ?

But we can also decide to have one dedicated RasPI per sm.