adds support for query by country
trying to add aggregate industries
removed defaultdict because I wasnt using it.
Changed try/except to use a in b idiom. Changed sort to use attrgetter. Moved sort outside for-loop.
Merge pull request #1 from technoskald/victims

Fixing industry merging
fixes the industry aggregation by using itemgetter instead of attrgetter.
code cleanup
improved ability to query by naics code.
improvements to the readme.