[SPARK-7399] [SPARK CORE] Fixed compilation error in scala 2.11

scala has deterministic naming-scheme for the generated methods which return default arguments . here one of the default argument of overloaded method has to be removed

Author: Tijo Thomas <tijoparacka@gmail.com>

Closes #5966 from tijoparacka/fix_compilation_error_in_scala2.11 and squashes the following commits:

c90bba8 [Tijo Thomas] Fixed compilation error in scala 2.11

core/src/main/scala/org/apache/spark/rdd/RDDOperationScope.scala

@@ -111,7 +111,7 @@ private[spark] object RDDOperationScope {
   private[spark] def withScope[T](
       sc: SparkContext,
       name: String,
-      allowNesting: Boolean = false)(body: => T): T = {
+      allowNesting: Boolean)(body: => T): T = {
     // Save the old scope to restore it later
     val scopeKey = SparkContext.RDD_SCOPE_KEY
     val noOverrideKey = SparkContext.RDD_SCOPE_NO_OVERRIDE_KEY