Support SSL/TLS mode for the Email SMTP connector

[maxidorius]

Thanks to #106, we found out that the Email SMTP connector can deal with STARTLS, but not with SSL/TLS. We need to configure the right properties in the connector.

We should create a new connector called smtps to handle and ignore the tls config key in it.

[maxidorius]

This mode can be enabled using the value 3 for the tls key.