Update CoffeeScript to 1.6.2

Sorry, this one is a bit messy.

The browser-friendly version at the 1.6.2 Git tag is actually 1.6.1, according to the version number embedded in the comment at the beginning of the file.
https://raw.github.com/jashkenas/coffee-script/1.6.2/extras/coffee-script.js

So I downloaded it from this commit, whose message is "CoffeeScript 1.6.2"
Commit: https://github.com/jashkenas/coffee-script/commit/a3e8de338a67d7d0d62096b1b025055bcac47a85
File: https://raw.github.com/jashkenas/coffee-script/a3e8de338a67d7d0d62096b1b025055bcac47a85/extras/coffee-script.js

The version number embedded in the minified file is 1.6.2, matching the commit message.

Also, FWIW, GitHub says that the commit that I pointed to is the last change to `extras/coffee-script.js`.
https://github.com/jashkenas/coffee-script/tree/master/extras