Fix tests

Author: andrewor14

core/src/test/scala/org/apache/spark/deploy/JsonProtocolSuite.scala

@@ -170,7 +170,7 @@ object JsonConstants {
     """
       |{"name":"name","cores":4,"memoryperslave":1234,
       |"user":"%s","sparkhome":"sparkHome",
-      |"command":"Command(mainClass,List(arg1, arg2),Map(),Map(),List(),List(),None)"}
+      |"command":"Command(mainClass,List(arg1, arg2),Map(),List(),List(),List())"}
     """.format(System.getProperty("user.name", "<unknown>")).stripMargin
 
   val executorRunnerJsonStr =