Support TLS connections to MQTT server

[andreasbrett]

Added support for TLS connection to the MQTT server. Configuration through 2 settings:

• Verify TLS connection by checking if MQTT server's certificate is signed by one of the CA certificates provided in the path MQTT_TLS_CACERTS
• If MQTT_TLS_INSECURE is set to True server name will not be checked against host name provided in server certificate (caution, as the name suggests this is insecure! only use in non-production environments)

[lolouk44]

Thanks for your PR.
I've had a quick look and can't see anything that would break at first glance.
That being said I don't use TLS now, never have before either, and unfortunately don't have time to set something up for testing right now.
I can publish a beta version of the repo and docker container if you can test and feedback on the TLS side?
I'll test on the non TLS with your version.
How does that sound

[andreasbrett]

Yes, I can test this end of this week (Mi Scale is still in delivery).

[lolouk44]

0.1.15a published.
Make sure you use the 0.1.15a tag in your docker-compose, not latest

[andreasbrett]

Tested and working! I did find a bug though with the default of MQTT_DISCOVERY, I'll create a separate PR for that.

I also checked if the retain=false works and it did.
#44