Import fixes. Import postfixOps explicitly.

Author: harishreedharan

core/src/main/scala/org/apache/spark/deploy/SparkHadoopUtil.scala

@@ -37,6 +37,7 @@ import org.apache.spark.util.Utils
 
 import scala.collection.JavaConversions._
 import scala.concurrent.duration._
+import scala.language.postfixOps
 
 /**
  * :: DeveloperApi ::

yarn/src/main/scala/org/apache/spark/deploy/yarn/AMDelegationTokenRenewer.scala

@@ -19,6 +19,8 @@ package org.apache.spark.deploy.yarn
 import java.security.PrivilegedExceptionAction
 import java.util.concurrent.{Executors, TimeUnit}
 
+import scala.language.postfixOps
+
 import org.apache.hadoop.conf.Configuration
 import org.apache.hadoop.fs.{FileSystem, Path}
 import org.apache.hadoop.security.UserGroupInformation

yarn/src/main/scala/org/apache/spark/deploy/yarn/YarnSparkHadoopUtil.scala

@@ -17,15 +17,15 @@
 
 package org.apache.spark.deploy.yarn
 
-import java.io._
+import java.io.File
 import java.util.regex.Matcher
 import java.util.regex.Pattern
 
 import scala.collection.mutable.HashMap
 import scala.util.Try
 
 import org.apache.hadoop.conf.Configuration
-import org.apache.hadoop.fs._
+import org.apache.hadoop.fs.Path
 import org.apache.hadoop.io.Text
 import org.apache.hadoop.mapred.{Master, JobConf}
 import org.apache.hadoop.security.Credentials