Update controller.js

This will fix Issue #5 and allows a route to pop up a modal, but nothing more complex for now
Can you put this function in its own method:

```js
this.listenTo(routerChannel.vent, 'route', this._onRoute);
```

And call `stopListening` in the `destroyModal` method?

```js
destroyModal: function (options) {
  this.stopListening(routerChannel.vent, 'route', this._onRoute);
  // ...
```