rce configuration

[dominiquehunziker]

In case one wants to run only rce-master & rce-robot to create a network of robots (-> there is no need to create a container filesystem at all, ie run only provision config) then the execution of the rce processes fails because the container filesystem does not exist. (Checked in settings parser.) Some rethinking of the configuration is necessary, either:

1. create individual files for each process (and one common for all processes?)
2. add some kind of 'necessary capability' flag to indicated whether the container filesystem is required (similar comm ports for WebSocket is only necessary for rce-robot)
3. move the validity checks out of the settings; but there was a reason why they were added there in the first place...