Support passing options to coffeescript

[pravi]

We'd like to use coffeescript 2 in Debian but it causes a build failure in rails because ES6 is default in coffeescript 2. See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1013218 so to move forward we need to transpile the coffeescript output to be able use it with execjs. Would it be possible for blade to add this option so we can use coffeescript 2?