generic clustering

[erik-romson]

Hi
I found your library interesting but I needed to cluster based on objects, not strings. see src/test/java/com/apporiented/algorithm/clustering/ClusterPersonTest.java for an example.

So I rewrote it to handle generics and added some streaming as well (a few more dependencies but only in test scope).

I realize that this is a big change (code wise anyway), so I'll stop here. If you are interested to merge, let me know and I'll clean it up and do whatever you want me to fix

[lbehnke]

Thanks for this contribution. It certainly makes sense to use generic cluster nodes and I'd like to merge it. So if you could resolve the merge conflicts and clean up the code that would be great.