new version of inf-ruby, compatible with enh-ruby-mode

This bring the inf-ruby in line with nonsequitur's newer (much newer than the one previously defined in this recipe), and my version has been patched for compatibility with enh-ruby-mode recipe. Nonsequitur's version works only with ruby-mode, mine works with both. I issued a pull request on Nonsequitur's version for my patch. If accepted, I will update this recipe to point to his repo.