Support binary data

Web workers can pass binary data, but this doesn't work in workerpool.

the stdio option for child processes was added a bit ago, and allows creation of the ipc channel, which can then be leveraged for sending binary data.

additionally there's the new cluster native module which automates a lot of this.

i'd love the workerpool API available on top of either one of these approaches so i can have a robust solution that works on both web and node.