Add branch-specific CHANGES.txt file to RAT excludes list

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-347@1433232 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/pom.xml

@@ -500,6 +500,7 @@ http://maven.apache.org/xsd/maven-4.0.0.xsd">
           <excludes>
             <exclude>CHANGES.txt</exclude>
             <exclude>CHANGES.HDFS-1623.txt</exclude>
+            <exclude>CHANGES.HDFS-347.txt</exclude>
             <exclude>.idea/**</exclude>
             <exclude>src/main/conf/*</exclude>
             <exclude>src/main/docs/**</exclude>