Add a recipe for auto-complete-sage.

[auto-complete-sage](https://github.com/stakemori/auto-complete-sage) provides an [auto-complete](https://github.com/auto-complete/auto-complete) source for [sage-shell-mode](https://github.com/stakemori/sage-shell-mode).
I am the author and the maintainer of [auto-complete-sage](https://github.com/stakemori/auto-complete-sage).

Please merge this pull request.