I've just unlocked my Moto G bootloader under Ubuntu Linux using the Motorola fastboot Files found in this thread:
I guess they are useful for all Moto G Linux users :p
There's no need to pait Bluetooth LowEnergy (BLE) devices. Enable on the phone in settings/AndroidWear/BetaHeartReate. Then simply start Ghostracer and watch the heart symbol turning from grey to white when it is connected to your heart rate strap...