Switch Stop to use SigTerm and Kill Process Properly On Windows
Switch Stop to use SigTerm and Kill Process Properly On Windows

Issue #42

**Bug**
I was seeing `stop` now working when the library was used inside of an electron app.

**Fix**
For osx, use SIGTERM to kill instead of SIGINT.

Also adds windows logic to kill the child process properly

Marak/say.js