Change to Pairing Mode

[zerox1212]

Current implementation is an open broadcast of BLE UART service. This should be changed to a pairing arrangement so that the software can easily remember the user's device and ignore other tire pyrometers in the area.

[zerox1212]

Implementation as of #2 is now based on GATT characteristics, but the issue remains. The solution should pair to a single device and remember it. If it can be secured even better, but not necessary.