Address Matei's comments

bin/stop-slaves.sh

...rc/main/scala/org/apache/spark/deploy/DeployMessage.scala

...cala/org/apache/spark/deploy/master/ApplicationInfo.scala

.../org/apache/spark/deploy/master/LeaderElectionAgent.scala

...rc/main/scala/org/apache/spark/deploy/master/Master.scala

...la/org/apache/spark/deploy/master/PersistenceEngine.scala

.../scala/org/apache/spark/deploy/master/RecoveryState.scala

...rg/apache/spark/deploy/master/SparkZooKeeperSession.scala

...ain/scala/org/apache/spark/deploy/master/WorkerInfo.scala

...he/spark/deploy/master/ZooKeeperLeaderElectionAgent.scala

...est/scala/org/apache/spark/deploy/JsonProtocolSuite.scala