Again, do we need a different notification class?  I'm thinking we can just go with the one `ExamplesNotification`, and that notification class can have a `failed_example_notifications` method like so:

``` ruby
def failed_example_notifications
  examples.select { |ex| ex.execution_result.status == :failed }.map { |ex| FailedExampleNotification.new(ex) }
end
```

...which is equivalent to `failure_notifications` in the case of the `dump_failures` notification but also provides a generalized mechanism in any of the notification methods to get the notification objects for the failures.