Include 'extra data' when returning list of results from filter / all operations

Hi Jacob, 

When using nap's filter() or all() operations and the collection_field setting the code is currently throwing away any other top level keys in the response besides the collection field. I want these others fields too. This changes makes the following work:

sample response:
{ 'total_results': 45, 
  'results': [ ..... list of results ......] }

results = Resource.all()
total_results = results.extra_data['total_results']

I hope it's useful.