adding in demoMode to the api which shows headers with no data

Should solve #31 

I added a demoMode variable to the api.js. When this variable is true, then the headers will show up if the data key is an empty array returned by the API
can you remove this console statement? logging is fine for dev / debugging, but for merged code we should try to follow the unix principle of the [Rule of Silence](http://www.faqs.org/docs/artu/ch01s06.html#id2878450)