689 Add color to overview page

Resolves #689.

http://jenkins.buttonweavers.com:8080/job/buttonmen-AdmiralJota/44/

This is mostly based on the examples from #689, but it also takes into account some elements from the examples in #604.

There will need to be modifications to this code later once users are allowed to configure their colors and when we revise how completed games are handled, but I think this resolves #689 itself.