[SPARK-8623] Hadoop RDDs fail to properly serialize configuration

Author: Sandy Ryza <sandy@cloudera.com>

Closes apache#7050 from sryza/sandy-spark-8623 and squashes the following commits:

58a8079 [Sandy Ryza] SPARK-8623. Hadoop RDDs fail to properly serialize configuration

core/src/main/scala/org/apache/spark/serializer/KryoSerializer.scala

@@ -36,7 +36,7 @@ import org.apache.spark.network.nio.{GetBlock, GotBlock, PutBlock}
 import org.apache.spark.network.util.ByteUnit
 import org.apache.spark.scheduler.{CompressedMapStatus, HighlyCompressedMapStatus}
 import org.apache.spark.storage._
-import org.apache.spark.util.BoundedPriorityQueue
+import org.apache.spark.util.{BoundedPriorityQueue, SerializableConfiguration, SerializableJobConf}
 import org.apache.spark.util.collection.CompactBuffer
 
 /**
@@ -94,8 +94,10 @@ class KryoSerializer(conf: SparkConf)
     // For results returned by asJavaIterable. See JavaIterableWrapperSerializer.
     kryo.register(JavaIterableWrapperSerializer.wrapperClass, new JavaIterableWrapperSerializer)
 
-    // Allow sending SerializableWritable
+    // Allow sending classes with custom Java serializers
     kryo.register(classOf[SerializableWritable[_]], new KryoJavaSerializer())
+    kryo.register(classOf[SerializableConfiguration], new KryoJavaSerializer())
+    kryo.register(classOf[SerializableJobConf], new KryoJavaSerializer())
     kryo.register(classOf[HttpBroadcast[_]], new KryoJavaSerializer())
     kryo.register(classOf[PythonBroadcast], new KryoJavaSerializer())