Merge pull request #863 from shivaram/etrain-ridge

mllib/src/main/scala/spark/mllib/regression/Lasso.scala

.../main/scala/spark/mllib/regression/LinearRegression.scala

...c/main/scala/spark/mllib/regression/RidgeRegression.scala

.../src/main/scala/spark/mllib/util/LassoDataGenerator.scala

...src/main/scala/spark/mllib/util/LinearDataGenerator.scala

mllib/src/main/scala/spark/mllib/util/MLUtils.scala

.../src/test/java/spark/mllib/regression/JavaLassoSuite.java

...ava/spark/mllib/regression/JavaLinearRegressionSuite.java

...java/spark/mllib/regression/JavaRidgeRegressionSuite.java

mllib/src/test/scala/spark/mllib/regression/LassoSuite.scala

.../scala/spark/mllib/regression/LinearRegressionSuite.scala

...t/scala/spark/mllib/regression/RidgeRegressionSuite.scala