If the Java yuicompressor reported an error, it would not raise an exception on the Ruby side. This is because the block of a popen3 command doesn't actually raise an exception.
Fixed this with using Open3.capture3 instead which reports job status explicitly.
Also switched to using strings natively instead of converting strings to streams, because these are still glitchy with respect to UTF-8 or other encodings. All streams should probably
be opened in "binary" mode explicitly.
Version 1.3.3