Add bindEvents

This calls `bindEvents` before `loadData` on every render. It makes dealing with `Backbone.sync` much cleaner.

Use case:

```js
myView = Ribcage.extend({
  afterInit: function () {
    this.model = new MyModel()
  }
, bindEvents: function () {
    this.listenTo(this.model, 'change', this.render, this);
  }
, loadData: function (cb) {
    this.model.once('sync', cb);
    this.model.fetch();
  }
});
```

Notes:
 * I didn't call it `beforeLoadData` because it has to run on every render, not just renders that load data.
 * I couldn't bind my events in `afterRender` because it doesn't get called if data isn't loaded yet. So the model would sync, but the event wouldn't be bound and the view wouldn't update
 * This is really useful in subviews because if the parent view is rendered the events don't disappear