Created KMeansCommons file for common code.  Created trait holding functions common to KMeans and KMeansMiniBatch objects.
Created KMeansCommons.KMeansCommons trait for common functions in private KMeans classes. Moved KMeansMiniBatch.{initRandom, initKMeansMiniBatchParallel} there
Change KMeansCommons.initKMeansMiniBatchParallel to KMeansCommons.initParallel
Modify KMeans to use initRandom, initParallel in KMeansCommons
Updated documentation for initRun/initParallel to specify that centers are only for one run.
Clean up calls to initRandom in KMeans
Updated KMeansMiniBatch to properly implement sampling and gradient step update
Modify KMeansMiniBatchSuite to test KMeansMiniBatch differences.  Given stochastic nature, use epsilons instead of direct comparison of floats.