recover some unintentional changes

Author: CodingCat

core/src/main/scala/org/apache/spark/deploy/master/ApplicationInfo.scala

@@ -75,7 +75,8 @@ private[deploy] class ApplicationInfo(
     }
   }
 
-  def addExecutor(worker: WorkerInfo, cores: Int, useID: Option[Int] = None): ExecutorDesc = {
+  private[master] def addExecutor(worker: WorkerInfo, cores: Int, useID: Option[Int] = None):
+      ExecutorDesc = {
     val exec = new ExecutorDesc(newExecutorId(useID), this, worker, cores, desc.memoryPerExecutorMB)
     executors(exec.id) = exec
     coresGranted += cores

core/src/main/scala/org/apache/spark/deploy/master/Master.scala

@@ -22,7 +22,7 @@ import java.net.URLEncoder
 import java.text.SimpleDateFormat
 import java.util.Date
 
-import scala.collection.mutable.{ListBuffer, ArrayBuffer, HashMap, HashSet}
+import scala.collection.mutable.{ArrayBuffer, HashMap, HashSet}
 import scala.concurrent.Await
 import scala.concurrent.duration._
 import scala.language.postfixOps