MAHOUT-1162: Adding BallKMeans and StreamingKMeans clustering algorithms

Additionally, besides the new algorithms there are new utility methods in
ClusteringUtils for casting between Vector types and computing various
clustering quality metrics: Dunn Index, Davies-Bouldin Index and the
Adjusted Rand Index.



git-svn-id: https://svn.apache.org/repos/asf/mahout/trunk@1480954 13f79535-47bb-0310-9956-ffa450edef68