KMeansClustering cause thread leak
#### Issue Description

i use KMeansClustering like KMeansTest.java
every client request, i get new kmeans object by KMeansClustering.setup()
but there is no way to destroy threads allocate by KMeansClustering 
after thousands or more request, too many threads cause crash

#### Version Information

* deeplearning4j ver newest
* windows 7 and centos 6.x
