Patch to add Literate CoffeeScript support

`.coffee.md` and `.litcoffee` files are included in preprocessing and will be treated by the CoffeeScript processor as literate; i.e. anything not indented -- from what I can tell by at least 6 spaces -- will be treated as a comment, and anything indented appropriately will be considered code.

I don't have a very comprehensive test setup but it seems to work fine now with both regular and literate CoffeeScript files (run through Ember-CLI).