SPARK-2482: Resolve sbt warnings during build

At the same time, import the `scala.language.postfixOps` and ` org.scalatest.time.SpanSugar._` cause `scala.language.postfixOps` doesn't work

Author: witgo <witgo@qq.com>

Closes #1330 from witgo/sbt_warnings3 and squashes the following commits:

179ba61 [witgo] Resolve sbt warnings during build

1 files changed, 6 insertions, 6 deletions

diff --git a/repl/src/main/scala/org/apache/spark/repl/SparkILoop.scala b/repl/src/main/scala/org/apache/spark/repl/SparkILoop.scala
index d9eeffa860..e56b74edba 100644
--- a/repl/src/main/scala/org/apache/spark/repl/SparkILoop.scala
+++ b/repl/src/main/scala/org/apache/spark/repl/SparkILoop.scala
@@ -15,15 +15,15 @@ import scala.tools.nsc._
 import scala.tools.nsc.backend.JavaPlatform
 import scala.tools.nsc.interpreter._
 
-import scala.tools.nsc.interpreter.{ Results => IR }
-import Predef.{ println => _, _ }
-import java.io.{ BufferedReader, FileReader }
+import scala.tools.nsc.interpreter.{Results => IR}
+import Predef.{println => _, _}
+import java.io.{BufferedReader, FileReader}
 import java.net.URI
 import java.util.concurrent.locks.ReentrantLock
 import scala.sys.process.Process
 import scala.tools.nsc.interpreter.session._
-import scala.util.Properties.{ jdkHome, javaVersion }
-import scala.tools.util.{ Javap }
+import scala.util.Properties.{jdkHome, javaVersion}
+import scala.tools.util.{Javap}
 import scala.annotation.tailrec
 import scala.collection.mutable.ListBuffer
 import scala.concurrent.ops
@@ -33,7 +33,7 @@ import scala.tools.nsc.io.{File, Directory}
 import scala.reflect.NameTransformer._
 import scala.tools.nsc.util.ScalaClassLoader._
 import scala.tools.util._
-import scala.language.{implicitConversions, existentials}
+import scala.language.{implicitConversions, existentials, postfixOps}
 import scala.reflect.{ClassTag, classTag}
 import scala.tools.reflect.StdRuntimeTags._