Scrolling up when we click on New filter

There's a little fix:

on https://github.com/Packet-Clearing-House/maptable/blob/master/src/components/Filters.js#L72

``` js
add() {
```

You'll need to prevent the default behavior of the <a href=#"> tag on click.

``` js
add(evt) {
    evt.preventDefault();
```
