Generic game setup tests

[glowacki-dev]

There are some constraints that we must follow while writing new games:

• It's not possible to store nested arrays in firebase, so we can't have those in G object - We currently don't have this issue anywhere, but it's easy to forget about it
• When socket.io fallbacks to long polling (at least that seems to be the cause) it doesn't quite like sending arrays as move argument (this causes nested array situation as well) - currently it seems to happen when starting new picturematch game and selected categories are sent as an array not wrapped in an object

It should be possible to create some generic, reusable tests to check for such limitations

[sentry-io]

Sentry issue: OCTOBOARD-SERVER-6