s|println|main/info|g

https://github.com/kumarshantanu/lein-sub/blob/4ddbb83359b2f9b6435ffd5b9c012b81e28de1ac/src/leiningen/sub.clj#L9

Use Leiningen's own logging facility?
```clojure
(main/info "Reading project from" sub-proj-dir)
```

... which I think is currently `(println)` under the hood anyways, but at least this makes consistent `lein-sub`'s messaging mechanism.