Style fix

Author: jerryshao

external/kafka/src/test/scala/org/apache/spark/streaming/kafka/DirectKafkaStreamSuite.scala

@@ -27,7 +27,7 @@ import scala.language.postfixOps
 import kafka.common.TopicAndPartition
 import kafka.message.MessageAndMetadata
 import kafka.serializer.StringDecoder
-import org.scalatest.{FunSuite, BeforeAndAfter, BeforeAndAfterAll}
+import org.scalatest.{BeforeAndAfter, BeforeAndAfterAll, FunSuite}
 import org.scalatest.concurrent.Eventually
 
 import org.apache.spark.{Logging, SparkConf, SparkContext}