Fix directory removal

[Timer]

As part of our kitchensink test, we nohup a few node processes that need to be cleaned up on script exit.

We need to figure out why this doesn't work: https://github.com/facebookincubator/create-react-app/blob/master/tasks/e2e-kitchensink.sh#L24

[chitchu]

Looked up the manual for kill and the -s switch requires a signal_name and not a signal_number. I reckon the line should be:

ps -ef | grep 'react-scripts' | grep -v grep | awk '{print $2}' | xargs kill -s KILL

[Timer]

@chitchu I believe that's the case for unix (travis), I'm not sure about appveyor though. Could you submit a PR changing this behavior and we can see what happens? 😄

[chitchu]

The message Device or resource busy still pops up. I'll have a deeper look into this. But if anyone with more experience in windows land can chime in that'd be great.