Serial (or Bluetooth) gateway support

[gnh1201]

Gateways that do not rely on well-known protocols such as WiFi or 3G/LTE provide data transmission only through serial or Bluetooth. For instance, gateways supporting LoRaWAN technology or satellite communication rarely, if ever, directly support Ethernet or WiFi, and even if they do, they are usually expensive.

We need to assess whether we can support serial or Bluetooth in this project.

[AkiaCode]

I have implemented a basic communication system using the PySerial library by creating a Serial class that transmits all data received from the web via serial.

[gnh1201]

@AkiaCode Thank you, and I will review your enhancements soon.