Enable strong-pm to be controlled from parent over node-ipc

This is all cut-n-paste from test-pmctl.js. I suggest deleting it, and modifying `test-pmctl.js` so that instead of doing the `.on('data'`, it instead uses the control channel to request the pm status, which includes the port. That would allow the stdout to not have to be piped from the child pm (which causes issues), and at the same time prove there is a control channel to the child process. It looks like you have all the code for this already, in your `test()` function.