Disallow game names with spaces

[jasonharrison]

Fix #459 by throwing an error when encountering a game name with spaces.

Checklist

• Use a separate branch in your local repo (not master).
• Test coverage is 100% (or you have a story for why it's ok).

[nicolodavis]

How about we do this instead?

• We just log an error if the game name is malformed (i.e. it contains spaces).
• We don't try to automatically fix this for people.

That way we only need to change stuff in game.js and the API stuff is automatically taken care of because a name mismatch will result in the game not being found anyway.