Fix for exception error when null options are passed

Also updated package.json to be platform independent

If no options are passed into express.session(), a null object is created which causes express to throw an exception during the "typeof string" check.

I've initialized any null options object with a blank string so it will pass the string check (my previous fix didn't allow sessionOptions to be cleared in a new session). I've also done the same as a precaution for the express.application.io options as well.

Additionally, I've created a prepublish script for coffee compilation that is platform independent (based on shelljs and shelljs-nodecli).