Return device serial number - now empty

[smellai]

{ "Ports": [ { "Name": "/dev/ttyACM0", "SerialNumber": "", "DeviceClass": "", "IsOpen": false, "IsPrimary": false, "Baud": 0, "BufferAlgorithm": "", "Ver": "x.x.x-dev", "NetworkPort": false, "VendorID": "0x2341", "ProductID": "0x804e" } ], "Network": false }