unicorn-worker-killler

For https://github.com/focuslight/focuslight/issues/18

This is to achieve

> And, Let me write additional notes here: GrowthForecast(Plack) respawns child processes after seving 100 requests as default. So, Even if it opens files everytime it will not address big issues. I think this is nice mechanism, in terms of reducing memory issues too, and this can be done using unicorn-worker-killer gem

I picked the default parameters by just copying from https://github.com/kzk/unicorn-worker-killer