message: add electrode locations for unicorn
diff: "battery_channel": 9,
  "num_rows" : 18,
  "eeg_channels" : [0, 1, 2, 3, 4, 5, 6, 7],
  + "eeg_names": "Fz,C3,Cz,C4,Pz,PO7,Oz,PO8",
  "accel_channels": [8, 9, 10],
  "gyro_channels": [11, 12, 13],
  "other_channels": [16],
  