Reduce dependencies

Hi,

For the Gatling project (http://gatling-tool.org), this lib would be very useful. Being written in Scala, depending on Guava doesn't bring much for us and it would increase significantly the size of our bundles.  

I copy-pasted the AbstractIterator class as it's the only one that doesn't really have a plain JDK equivalent. 

What do you think ? 

Thanks
Nicolas