Fixed HdfsUtils to handle append in local file system

Author: tdas

streaming/src/main/scala/org/apache/spark/streaming/util/HdfsUtils.scala

@@ -27,7 +27,7 @@ private[streaming] object HdfsUtils {
     // If the file exists and we have append support, append instead of creating a new file
     val stream: FSDataOutputStream = {
       if (dfs.isFile(dfsPath)) {
-        if (conf.getBoolean("hdfs.append.support", false)) {
+        if (conf.getBoolean("hdfs.append.support", false) || dfs.isInstanceOf[RawLocalFileSystem]) {
           dfs.append(dfsPath)
         } else {
           throw new IllegalStateException("File exists and there is no append support!")