update test to look at one stage attempt

Author: squito

core/src/test/resources/HistoryServerExpectations/applications/local-1426533911241/stages/0/json_expectation renamed to core/src/test/resources/HistoryServerExpectations/applications/local-1426533911241/stages/0/0/json_expectation

@@ -1,4 +1,4 @@
-[ {
+{
   "status" : "Complete",
   "stageId" : 0,
   "attemptId" : 0,
@@ -239,4 +239,4 @@
       "diskBytesSpilled" : 0
     }
   }
-} ]
+}

core/src/test/scala/org/apache/spark/deploy/history/HistoryServerSuite.scala

@@ -80,7 +80,7 @@ class HistoryServerSuite extends FunSuite with BeforeAndAfter with Matchers with
     "one stage json" -> "applications/local-1422981780767/stages/1",
     "one stage attempt json" -> "applications/local-1422981780767/stages/1/0",
     "stage list with accumulable json" -> "applications/local-1426533911241/stages",
-    "stage with accumulable json" -> "applications/local-1426533911241/stages/0",
+    "stage with accumulable json" -> "applications/local-1426533911241/stages/0/0",
     "rdd list storage json" -> "applications/local-1422981780767/storage/rdd",
     "one rdd storage json" -> "applications/local-1422981780767/storage/rdd/0"
     //TODO multi-attempt stages