[R]: update unit tests on kmeans.
[R]: update unit tests on kmeans.

flashxio/FlashX,flashxio/FlashX,flashxio/FlashX,icoming/FlashX,flashxio/FlashX,icoming/FlashX,icoming/FlashX,flashxio/FlashX,icoming/FlashX,flashxio/FlashX,icoming/FlashX