Made mu, sigma private[mllib] members of MultivariateGaussian

Moved MultivariateGaussian (and test suite) from stat.impl to stat.distribution (required updates in GaussianMixture{EM,Model}.scala)
Marked MultivariateGaussian as @DeveloperAPI
Fixed style error

Author: tgaloppo

mllib/src/main/scala/org/apache/spark/mllib/clustering/GaussianMixtureEM.scala

@@ -22,7 +22,7 @@ import scala.collection.mutable.IndexedSeq
 import breeze.linalg.{DenseVector => BreezeVector, DenseMatrix => BreezeMatrix, diag, Transpose}
 import org.apache.spark.rdd.RDD
 import org.apache.spark.mllib.linalg.{Matrices, Vector, Vectors}
-import org.apache.spark.mllib.stat.impl.MultivariateGaussian
+import org.apache.spark.mllib.stat.distribution.MultivariateGaussian
 import org.apache.spark.mllib.util.MLUtils
 
 /**

mllib/src/main/scala/org/apache/spark/mllib/clustering/GaussianMixtureModel.scala

@@ -21,7 +21,7 @@ import breeze.linalg.{DenseVector => BreezeVector}
 
 import org.apache.spark.rdd.RDD
 import org.apache.spark.mllib.linalg.{Matrix, Vector}
-import org.apache.spark.mllib.stat.impl.MultivariateGaussian
+import org.apache.spark.mllib.stat.distribution.MultivariateGaussian
 import org.apache.spark.mllib.util.MLUtils
 
 /**

mllib/src/main/scala/org/apache/spark/mllib/stat/impl/MultivariateGaussian.scala renamed to mllib/src/main/scala/org/apache/spark/mllib/stat/distribution/MultivariateGaussian.scala

@@ -15,12 +15,13 @@
  * limitations under the License.
  */
 
-package org.apache.spark.mllib.stat.impl
+package org.apache.spark.mllib.stat.distribution
 
 import breeze.linalg.{DenseVector => DBV, DenseMatrix => DBM, diag, max, eigSym}
 
-import org.apache.spark.mllib.linalg.{ Vectors, Vector, Matrices, Matrix }
+import org.apache.spark.mllib.linalg.{Vectors, Vector, Matrices, Matrix}
 import org.apache.spark.mllib.util.MLUtils
+import org.apache.spark.annotation.DeveloperApi;
 
 /**
  * This class provides basic functionality for a Multivariate Gaussian (Normal) Distribution. In
@@ -31,9 +32,10 @@ import org.apache.spark.mllib.util.MLUtils
  * @param mu The mean vector of the distribution
  * @param sigma The covariance matrix of the distribution
  */
+@DeveloperApi
 class MultivariateGaussian private[mllib] (
-    val mu: DBV[Double], 
-    val sigma: DBM[Double]) extends Serializable {
+    private[mllib] val mu: DBV[Double], 
+    private[mllib] val sigma: DBM[Double]) extends Serializable {
 
   require(sigma.cols == sigma.rows, "Covariance matrix must be square")
   require(mu.length == sigma.cols, "Mean vector length must match covariance matrix size")

mllib/src/test/scala/org/apache/spark/mllib/stat/impl/MultivariateGaussianSuite.scala renamed to mllib/src/test/scala/org/apache/spark/mllib/stat/distribution/MultivariateGaussianSuite.scala

@@ -15,7 +15,7 @@
  * limitations under the License.
  */
 
-package org.apache.spark.mllib.stat.impl
+package org.apache.spark.mllib.stat.distribution
 
 import org.scalatest.FunSuite