Add unsubscribe link to email template

[rizomaa]

1. To check it online

[ArtyomKr]

@rizomaa I added it in my template, #128 (comment)

[wellemut]

We are working on the same issue at the moment: kartevonmorgen/kvmflows#4

[rizomaa]

@ArtyomKr please make PR to template forlder here: https://github.com/diglabby/mapa-subscription