Promise and request fixes

- Promise.all now increments its internal counter of completed promises.
- node and xhr requests now set the statusCode and property on their
  return responses, and xhr sets statusText.
- The base request function now assigns the proper value to the data
  property of the resolved response.
Promise updates

- Return an Array when an Array is given to Promise.all
- Update abort implementaiton (still broken)
- Propagate progress updates
- Add a `finally` method (like `always` in Dojo 1 Promises)