- Move mail functions to its own packages;
- Move bigger router functions to its own functions, and separate
router creation from main function;
- Edit the algorithm that choses the format will be chosen with
regards to format preference to a simples one.
This commits adds support for rendering email in text/html,
text/markdown and text/plain inside a MIME/multipart mail.
Bluemonday was added as a dependency and initialized but it is still not
used because the styling of the email is "discarted" too much. But this
needs to be fixed before going to production.
