Requiring YAML

I was having this:

```
/Users/victor.martins/.rbenv/versions/1.9.3-p484/lib/ruby/gems/1.9.1/gems/fudge-0.4.0/lib/fudge/tasks/composite_task.rb:40:in `fudge_settings': uninitialized constant Fudge::Tasks::CompositeTask::YAML (NameError)
```

And that fixed it. :)