Fixes to Cloud Files examples from PR #50

Continue from #50 
According to the [Javadoc for writeFrom](http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/io/ByteSink.html#writeFrom(java.io.InputStream\)), it does *not* close the input stream.

@andrewgaul @everett-toews: is that OK?