Fix browser caching

I see a potential caching issue whereby the browser may hang on to previously loaded json for a couple of minutes (depending on the browser). Easily fixed by referencing the .json file with an arbitrary value to negate the caching:

So, change:

```
function fetchData() {
$.getJSON('/data.json', function(data) {
var stillhere = {}
```

to:

```
function fetchData() {
var time = new Date().getTime();
$.getJSON('/data.json?' + time, function(data) {
var stillhere = {}
```