[Streaming][minor] Remove additional quote and unneeded imports

Author: jerryshao <[email protected]>

Closes apache#5540 from jerryshao/minor-fix and squashes the following commits:

ebaa646 [jerryshao] Minor fix

Author: jerryshao

examples/scala-2.10/src/main/scala/org/apache/spark/examples/streaming/DirectKafkaWordCount.scala

@@ -41,7 +41,7 @@ object DirectKafkaWordCount {
         |  <brokers> is a list of one or more Kafka brokers
         |  <topics> is a list of one or more kafka topics to consume from
         |
-        """".stripMargin)
+        """.stripMargin)
       System.exit(1)
     }
 

external/kafka/src/main/scala/org/apache/spark/streaming/kafka/KafkaRDD.scala

@@ -23,10 +23,9 @@ import org.apache.spark.{Logging, Partition, SparkContext, SparkException, TaskC
 import org.apache.spark.rdd.RDD
 import org.apache.spark.util.NextIterator
 
-import java.util.Properties
 import kafka.api.{FetchRequestBuilder, FetchResponse}
 import kafka.common.{ErrorMapping, TopicAndPartition}
-import kafka.consumer.{ConsumerConfig, SimpleConsumer}
+import kafka.consumer.SimpleConsumer
 import kafka.message.{MessageAndMetadata, MessageAndOffset}
 import kafka.serializer.Decoder
 import kafka.utils.VerifiableProperties