Make the game ID more prevalent to users

[wwilsman]

Currently to join a game that was created by another player you have to manually go to the URL for that game. I'd like to do 2 things regarding this:

• Show the game ID somewhere besides the URL after the game is created.
• From the welcome screen, allow entering a game ID to take you to that route.
• Remove lowercase characters from game ID.

I think these two things will improve UX greatly when joining a game.