nimrod-lang: New and improved formulas

This pull request attempts to improve Homebrew's support for the Nimrod language by supplying two new and improved formulas. The explanation for the changes are in the commits themselves, and I'd also be happy to answer any questions about this here.
Please submit a pull request to https://github.com/Araq/Nimrod.git with this patch, add a Ruby comment pointing to the pull request you created and explain why the patch is needed.