Add support for votes

[Jonathan-Zollinger]

support zendesk votes (on articles only)

• List Votes
• Show Vote
• Create Vote
• Delete Vote

This is complete when docs are supplemented with example usage (both successful calls and failures), and tests validate Zendesk's documented behavior - successful calls and failures (i.e. the updateUserSegment endpoint returns a 200 error code and the userSegmentObject created, thus tests should validate this and nothing more).