Vistrails integration

Added display_dict widget to display a nested dictionary

Added a generic query widget that acts as a front end for the data broker and uses display_dict to show the results from the data broker.  This widget could be used as a template for any query/result

This may not be entirely ready to be merged into master, but it should at least be on everyone's radar as I will not be working on it for the next 5 days
should be `self._search_func` ?