remove unused imports from RDDSuite

Author: dorx

core/src/test/scala/org/apache/spark/rdd/RDDSuite.scala

@@ -22,12 +22,8 @@ import scala.reflect.ClassTag
 
 import org.scalatest.FunSuite
 
-import org.apache.commons.math3.distribution.BinomialDistribution
-import org.apache.commons.math3.distribution.PoissonDistribution
-
 import org.apache.spark._
 import org.apache.spark.SparkContext._
-import org.apache.spark.rdd._
 
 class RDDSuite extends FunSuite with SharedSparkContext {