Adjust voting dapp to work with new voting smart contract interface

[Victor-N-Suadicani]

Purpose

The voting smart contract was simplified and the interface changed slightly, so this needed adjustment as well.

Changes

Made the dapp conform to the new interface, primarily changing from using indices to using the options as strings.

Checklist

• My code follows the style of this project.
• The code compiles without warnings.
• I have performed a self-review of the changes.
• I have documented my code, in particular the intent of the
  hard-to-understand areas.
• (If necessary) I have updated the CHANGELOG.

[DOBEN]

LGTM