Fixes breaking bug if no suggested spelling results were returned.

Just a small fix - in cases where no spelling suggest results were returned, it was possible for a KeyError exception to be thrown (and happened to me).

Good description of the crash case is here.  http://stackoverflow.com/questions/18961894/haystack-keyerror-in-the-elasticsearch-backend-module

Verified working here.  Thanks for the great work on django-haystack!