add the mocha-snippets recipe.

This provides very common snippets when writing testcases in JavaScript
using [mocha][1]

Here is the package repository of which I am the maintainer:

https://github.com/cowboyd/mocha-snippets.el

I've been using these snippets for over a year, and decided to extract a
subset of them so that I could share with my co-workers and the world.

1: http://visionmedia.github.io/mocha/

recipes/mocha-snippets

@@ -0,0 +1,4 @@
+(mocha-snippets
+ :repo "cowboyd/mocha-snippets.el"
+ :fetcher github
+ :files ("*.el" "snippets"))