Use through2 instead of event-stream.through for a more complete stream interface

I had to monkey-patch gulp-cjsx locally in order to use through 2 so i could unpipe streams.
There is no disadvantage to using through2 instead of event-stream.through
Also updated tests to use unix style \\\\ file-paths, which through2 uses.
Since you are adding through2, we don't need event-stream anymore.