[SPARK-15104] Fix spacing in log line

Otherwise get logs that look like this (note no space before NODE_LOCAL)

```
INFO  [2016-05-03 21:18:51,477] org.apache.spark.scheduler.TaskSetManager: Starting task 0.0 in stage 101.0 (TID 7029, localhost, partition 0,NODE_LOCAL, 1894 bytes)
```

Author: Andrew Ash <andrew@andrewash.com>

Closes #12880 from ash211/patch-7.

core/src/main/scala/org/apache/spark/scheduler/TaskSetManager.scala

@@ -479,7 +479,7 @@ private[spark] class TaskSetManager(
           // val timeTaken = clock.getTime() - startTime
           val taskName = s"task ${info.id} in stage ${taskSet.id}"
           logInfo(s"Starting $taskName (TID $taskId, $host, partition ${task.partitionId}," +
-            s"$taskLocality, ${serializedTask.limit} bytes)")
+            s" $taskLocality, ${serializedTask.limit} bytes)")
 
           sched.dagScheduler.taskStarted(task, info)
           return Some(new TaskDescription(taskId = taskId, attemptNumber = attemptNum, execId,