force to kill instance on windows

i would recommend to force the killing process and use the PID
https://github.com/bitovi/launchpad/blob/master/lib/local/instance.js#L90
should be: `command = 'taskkill /f /pid ' + this.id;`

on my windows machine the `taskkill` was not working an node will not exit because a chrome will still exists

Open lib/local/instance.js at line 90 and inspect how the instance process is terminated on Windows. Reproduce the case where Chrome remains and Node does not exit, then verify that PID-based termination makes the instance shut down cleanly.

Written by the indexing model from the issue text.