Recursively check package directories for .hs files

The current Packages only checks in `.` and `src` for `.hs` files so if you have a path like `src/Language/Fay/JQuery.hs` without a `.hs` directly under `src` you'll get a unable to find package error even though the path is correct.

This change looks recursively in the directories, which does mean that both `.` and `src` are added, but it seems like they were both added anyway.