Upgrade to nodemailer 1.0.1

/to @ritch 
If you specify a type that is not 'stub' (such as `smtp`), this will fail unless you explicitly add `nodemailer-smtp-transport` to your project's package.json.

I would recommend we add `nodemailer-smtp-transport` and `nodemailer-direct-transport` to loopback's package.json so they are available here without an explicit install.