add recipe for colemak-evil

Colemak is an alternative keyboard layout, and [Colemak Evil](https://github.com/patbl/colemak-evil) is a set of remappings that makes using Evil's Vim-like keybindings in Emacs more pleasant. Colemak Evil is based on [a set of remappings for Vim](http://forum.colemak.com/viewtopic.php?id=50) used by the creator of Colemak. It's a rather small niche, but someone else suggested that it be added to Melpa, so at least a couple of people would benefit.

I'm the maintainer.