[SPARK-6374] [MLlib] add get for GeneralizedLinearAlgo

I find it's better to have getter for NumFeatures and addIntercept within GeneralizedLinearAlgorithm during actual usage, otherwise I 'll have to get the value through debug.

Author: Yuhao Yang <hhbyyh@gmail.com>

Closes #5058 from hhbyyh/addGetLinear and squashes the following commits:

9dc90e8 [Yuhao Yang] add get for GeneralizedLinearAlgo

mllib/src/main/scala/org/apache/spark/mllib/regression/GeneralizedLinearAlgorithm.scala

@@ -123,6 +123,11 @@ abstract class GeneralizedLinearAlgorithm[M <: GeneralizedLinearModel]
    */
   private var useFeatureScaling = false
 
+  /**
+   * The dimension of training features.
+   */
+  def getNumFeatures: Int = this.numFeatures
+
   /**
    * The dimension of training features.
    */
@@ -141,6 +146,11 @@ abstract class GeneralizedLinearAlgorithm[M <: GeneralizedLinearModel]
    */
   protected def createModel(weights: Vector, intercept: Double): M
 
+  /**
+   * Get if the algorithm uses addIntercept
+   */
+  def isAddIntercept: Boolean = this.addIntercept
+
   /**
    * Set if the algorithm should add an intercept. Default false.
    * We set the default to false because adding the intercept will cause memory allocation.