Added model events for -created, -updated and -deleted

Usage:

```javascript
BD.store.on('invoice-created', function(invoice) {
  console.log('Weehooo! Invoice no. '+invoice.get('invoiceNo')+' was created :)');
});

BD.store.on('invoice-updated', function(invoice) {
  console.log('Weehooo! Invoice no. '+invoice.get('invoiceNo')+' was updated :)');
});

BD.store.on('invoice-deleted', function(invoice) {
  console.log('Booohooo! Invoice no. '+invoice.get('invoiceNo')+' was deleted :(');
});
```