The GSM module should connect to the MQTT broker

[sagaraivale]

• GSM module must be able to connect to the MQTT broker.
• It must have sent/receive payload data to/from the MQTT broker.
• The backend should be implemented in Go lang.

[sagaraivale]

@lioramilbaum, @nilhase25: Please let me know ur thoughts/suggestions here.

[lmilbaum]

Same comment as with the previous issue. Add the high level design to the readme.

[sagaraivale]

@lioramilbaum: Yes, I will add a basic architecture diagram and update the readme file.