Refactoring back half of quiz

[cynthiarich]

This PR finishes up the refactor of the quiz. There are lots of changes in here (sorry 😞 ) but here's an overview of what's changed:

• Add final scores to global state to show on result page.
• Add an "endgame" socket to push users to the results page after the last question
• Move code out of routes and into the controllers so that the server can control the flow of the quiz
• Increment games won and games played at the end of the game
• Remove a bunch of unused vars and routes