Fix some spelling error

Minor changes,fix some spelling error.

Author: wankunde <wankunde@163.com>

Closes #516 from wankunde/master.
diff --git a/measure/src/main/scala/org/apache/griffin/measure/launch/batch/BatchDQApp.scala b/measure/src/main/scala/org/apache/griffin/measure/launch/batch/BatchDQApp.scala
index fe03508..4c8e7b9 100644
--- a/measure/src/main/scala/org/apache/griffin/measure/launch/batch/BatchDQApp.scala
+++ b/measure/src/main/scala/org/apache/griffin/measure/launch/batch/BatchDQApp.scala
@@ -57,7 +57,7 @@
     conf.setAll(sparkParam.getConfig)
     conf.set("spark.sql.crossJoin.enabled", "true")
     sparkSession = SparkSession.builder().config(conf).enableHiveSupport().getOrCreate()
-    var logLevel = getGriffinLogLevel()
+    val logLevel = getGriffinLogLevel()
     sparkSession.sparkContext.setLogLevel(sparkParam.getLogLevel)
     griffinLogger.setLevel(logLevel)
     sqlContext = sparkSession.sqlContext
diff --git a/measure/src/main/scala/org/apache/griffin/measure/launch/streaming/StreamingDQApp.scala b/measure/src/main/scala/org/apache/griffin/measure/launch/streaming/StreamingDQApp.scala
index 502f8cb..e80ac61 100644
--- a/measure/src/main/scala/org/apache/griffin/measure/launch/streaming/StreamingDQApp.scala
+++ b/measure/src/main/scala/org/apache/griffin/measure/launch/streaming/StreamingDQApp.scala
@@ -63,7 +63,7 @@
     conf.setAll(sparkParam.getConfig)
     conf.set("spark.sql.crossJoin.enabled", "true")
     sparkSession = SparkSession.builder().config(conf).enableHiveSupport().getOrCreate()
-    var logLevel = getGriffinLogLevel()
+    val logLevel = getGriffinLogLevel()
     sparkSession.sparkContext.setLogLevel(sparkParam.getLogLevel)
     griffinLogger.setLevel(logLevel)
     sqlContext = sparkSession.sqlContext
diff --git a/measure/src/main/scala/org/apache/griffin/measure/step/transform/TransformStep.scala b/measure/src/main/scala/org/apache/griffin/measure/step/transform/TransformStep.scala
index 8c094b2..b3318ba 100644
--- a/measure/src/main/scala/org/apache/griffin/measure/step/transform/TransformStep.scala
+++ b/measure/src/main/scala/org/apache/griffin/measure/step/transform/TransformStep.scala
@@ -44,7 +44,7 @@
 
   def execute(context: DQContext): Boolean = {
     val threadName = Thread.currentThread().getName
-    info(threadName + " bigin transform step : \n" + debugString())
+    info(threadName + " begin transform step : \n" + debugString())
     // Submit parents Steps
     val parentStepFutures = parentSteps.filter(checkAndUpdateStatus).map { parentStep =>
       Future {