expose SMTP server settings

dino tries to send PW reset and mail confirmation emails, but there is no way to set an SMTP server.

- [ ] expose the following django settings:
  * `EMAIL_HOST`
  * `EMAIL_HOST_USER`
  * `EMAIL_HOST_PASSWORD`
  * `EMAIL_PORT`
  * `EMAIL_USE_TLS`
  * `EMAIL_USE_SSL`
- [ ] set `EMAIL_BACKEND` to `console.EmailBackend`, if in DEBUG mode, otherwise leave the default SMTP backend