Use https://github.com/heroku/heroku-buildpack-apt to
install protobuf-compiler and libprotobuf-dev which are needed by cid3

* Allow SMTP auth method customization

* Add SMTP openssl_verify_mode option support

Allows one use self-signed certs with their SMTP server.

* Add SMTP enable_starttls_auto option support

Allows the user to set the address mastodon emails are maraked as being sent from