Fixed TimeSpan bug (issue #11)

I couldn't make your build file work (build.ps1) it gave me a lot of errors.
Is there a special reason you used PowerShell for build and not Grunt for example? It just seems like not the right tool for the job.
If you help me fix the build then I can push the new artifacts. I think the the built endgame.js doesn't go to the tests directory (or maybe this was caused by the build script error).

If you get the time, ping me on IRC #freenode (zbzzn or zbzzn_)
or twitter @zbzzn