suggested improvements to output JSON format

[tarheel]

From Chris Jerdonek:

• Since the format uses candidate names for the keys, it would be good to have the list of candidates in a contest definition / manifest section. That way you don't need to look inside the round data to get this info. You probably also want the ability to link the candidates to ID's that are used elsewhere in the system (so you're not matching strings that might have differences).
• It would be good to have separate totals for the various categories of continuing ballots, exhausted by overvote, etc.
• For government use, we probably want to have a lot of these numbers also subdivided at the precinct level (for statement-of-vote style reporting, etc).