Add settings for TLS and mail server authentication to EmailService

[matsbov]

This PR adds the possibility to use TLS and mail server authentication with the EmailService (used for notifications about downloaded records).

Using these options may look like this in the config file:

mail.smtp.host=mail.example.com
mail.smtp.port=587
mail.smtp.starttls.enable=true
[email protected]
mail.smtp.password=abc123

[vjrj]

What I do to avoid this is to use localhost and configure a postfix with the real configuration (with ssl, etc).

I configure all the servers that use mail also via ansible:
https://github.com/AtlasOfLivingAustralia/documentation/wiki/Postfix-configuration

[matsbov]

Yes, we also had a separate in-between postfix. However, all other services we have were already talking directly to the real mailserver so we could now get rid of the postifx. Personally I prefer it this way with one component less.

[vjrj]

Uppps, for a moment I forget that you are using docker. Sorry.