Use gh-pages to render map

It looks like GitHub stops rendering marker popups after 200 or so features. This PR uses GitHub pages to render your own map. You can see it at http://jasonsanford.github.io/GeoJSON-Ballparks/. If you merge this and create a new gh-pages branch after you can view your own at http://cageyjames.github.io/GeoJSON-Ballparks/. Then you'll have the ability to style out the markers, map, and popups all you want.