Use child_process.spawn instead of child_process.exec

[headcr4sh]

When using the closure-compiler-stream on many files / a huge amount of JavaScript sources, I receive the following error message:

Error: stdout maxBuffer exceeded.
    at Socket.<anonymous> (child_process.js:689:13)
    at Socket.emit (events.js:95:17)
    at Socket.<anonymous> (_stream_readable.js:764:14)
    at Socket.emit (events.js:92:17)
    at emitReadable_ (_stream_readable.js:426:10)
    at emitReadable (_stream_readable.js:422:5)
    at readableAddChunk (_stream_readable.js:165:9)
    at Socket.Readable.push (_stream_readable.js:127:10)
    at Pipe.onread (net.js:528:21)

I assume (but I am NOT quite sure) that this is due to the fact that child_process.exec buffers everything that is being written to stdout before invoking the callback function. child_process.spawn on the other hand doesn't do that and seems to be a much cleaner solution, therefore.