Add ability to run binary votes

[XertroV]

Add a flag in SC for binary votes (instead of range voting)

Probs best to set binary votes to only -1 or 1 (within range voting data struct) - means we can run the same algorithm as before and the total votes that come out will be easy to read (e.g. positive result means it passed)

Probs also best to introduce a vote flag instead of just for binary votes (e.g. a uint or enum)

• UI should check vote flag and enforce in UI
• SC should have vote flag
• Auditor should check binary flag and enforce when counting votes (ideally gracefully changing a -3 to a -1 instead of rejecting outright)
• compatible w/ both encrypted and plaintext ballots