solder sensor cables to the PSLabs

Currently the sensor cables are simply plugged into the pins of the PSLabs. However, this does not only look bad, it also does not really fit inside the box (unless when bending the pins, which should not be done in the long therm). Therefore, it would be best to unsolder all pins from the PSLabs and instead solder on the cable ends of those sensors (for the wiring logic please look at the readme in the "sensors" folder) directly on to the PSLabs.