Add '.iced' as a recognized extension

[IcedCoffeeScript](http://maxtaco.github.com/coffee-script/) is an extension of CoffeeScript, with two new keywords (`await` and `defer`) that look just like function calls. So the syntax highlighting for CoffeeScript is fine for IcedCoffeeScript as well.

Therefore, it would be nice if coffee-script-tmbundle recognized `.iced` as an extension that should be treated as CoffeeScript.

Start by locating the coffee-script-tmbundle extension-to-language mapping. Add `.iced` to the extensions treated as CoffeeScript, then verify that IcedCoffeeScript files receive the existing CoffeeScript syntax highlighting.

Written by the indexing model from the issue text.