JSON Local Storage – How to Load a Local JSON File

Is there a way to configure firefox using about:config to allow local file access (for demo purposes)?

Specifically using FF12, I need to be able to have local file access to json data. It runs fine on a server, but I'd like to make this demo more portable.

        $.ajax({
            url: "../_assets/levelschema.json",
            complete: function (data) {
                Levels = data.levels;
                //...
            },
            success: function (data) {                    
                // wont get called b/c files don't have 200 HTTP status
            },
            async: false
        });

I've tried setting it to not async=false, but I get a "Access to restricted URI denied" error. This is a security feature. I really need the demo to work offline, without internet access, and I'd prefer the people using it not have to install a web server. I'd also prefer not having to embed all my data in the HTML tags since that data subject to change.