A rounding error

[i-fail]

Hi. Sorry, I'm new to github, not sure if I did this by the book. I found a major rounding error in your calculations of requests/second, because you were dividing by the rounded number of seconds instead of the actual time passed. That would give you very incorrect results for short tests. I fixed it and I pushed it here:

https://github.com/i-fail/gobench-windows

I also needed a windows binary, which your repo didn't have, added that too.

Thank you for this useful tool!