Add/update some libraries

- Update MailHog path and description
- add envconf/gofigure/smtp/websysd/purl/go-log/goose/linkio
Personally, I think just changing the link to point to http://godoc.org/github.com/ian-kent/linkio instead of the github page is the easiest thing to do.

That way there's no chance to have a stale README because you updated the code but forgot to update the README.