[SPARK-5132][Core]Correct stage Attempt Id key in stageInfofromJson

SPARK-5132:
stageInfoToJson: Stage Attempt Id
stageInfoFromJson: Attempt Id

Author: hushan[胡珊] <hushan@xiaomi.com>

Closes apache#3932 from suyanNone/json-stage and squashes the following commits:

41419ab [hushan[胡珊]] Correct stage Attempt Id key in stageInfofromJson

core/src/main/scala/org/apache/spark/util/JsonProtocol.scala

@@ -530,7 +530,7 @@ private[spark] object JsonProtocol {
 
   def stageInfoFromJson(json: JValue): StageInfo = {
     val stageId = (json \ "Stage ID").extract[Int]
-    val attemptId = (json \ "Attempt ID").extractOpt[Int].getOrElse(0)
+    val attemptId = (json \ "Stage Attempt ID").extractOpt[Int].getOrElse(0)
     val stageName = (json \ "Stage Name").extract[String]
     val numTasks = (json \ "Number of Tasks").extract[Int]
     val rddInfos = (json \ "RDD Info").extract[List[JValue]].map(rddInfoFromJson(_))