combine "Zero Sum Games" and "Zer0Sum Games"

they were both created just recently (since stardrive is coming out). Steam Refers to it as Zero Sum Games, the logo build and the developer on the kickstarter used "Zer0Sum Games".

I think Zer0Sum Games should be deleted, but the name added as an alias to Zero Sum Games. Or vice-versa.

@riboflavin: Done.