VILLASnodeManager: villas-controller crashes if there is no villas-node running

[bekiralti]

VILLASnodeManager (actually the entire villas-controller) crashes as soon as the line

self._status = self.node.status

in VILLASnodeManager.__init__() is reached. This happens because self.node.status is trying to request the status from a running villas-node process. However if no villas-node process is running at this point this line crashes with urllib.error.URLError.

I can send my example configuration for villas-controller if necessary.