Add support for SSL/TLS

[Rosen01]

Answer to issue #32.

Signed-off-by: Daniel Rosengarten github@praetorians.be

[Rosen01]

I've tested the code and it works for me.
It's retro-compatible with old code.

MQTTS (without Root CA validation -> unsecure)
EspMQTTClient client(wifi_ssid, wifi_password, mqtt_host, mqtt_login, mqtt_password, host, mqtt_port)

MQTTS (with Root CA validation)
EspMQTTClient client(wifi_ssid, wifi_password, mqtt_host, mqtt_login, mqtt_password, mqtt_ca_cert, host, mqtt_port)

MQTTS with client certificate
EspMQTTClient client(wifi_ssid, wifi_password, mqtt_host, mqtt_login, mqtt_password, mqtt_ca_cert, mqtt_client_cert, mqtt_client_key, host, mqtt_port)

[plapointe6]

Thanks a lot, I will take time to review this soon :)

[jordiyapz]

Hi, any update on the review?? @plapointe6

[yasiralijaved]

Hi, any update on this? I am trying to use this lib but can not move forward due to this limitation.