clean imports

Author: James Lee

src/main/java/com/sparkTutorial/advanced/accumulator/StackOverFlowSurvey.java

@@ -4,7 +4,6 @@
 import org.apache.spark.SparkContext;
 import org.apache.spark.api.java.JavaRDD;
 import org.apache.spark.api.java.JavaSparkContext;
-import org.apache.spark.util.AccumulatorV2;
 import org.apache.spark.util.LongAccumulator;
 import scala.Option;