Adding the ability to compile literal CoffeeScript files

Literal CoffeeScript is great. It let you write markdown text with all code blocks being at the end transformed into the final js source. I'm for example writing a sample of a literal CoffeeScript file. This block will be part of the final code:

    pr = new PullRequest

You can have a very easy-reading code, as you explain what you do. Here we'll accept the pull request :+1: :

    ok = pr.accept()
    alert 'sorry' unless ok

The plugins now can compile files ending with `.litcoffee` and `.coffee.md` as literal CoffeeScript files.