Fixed CHANGES.txt to track Release 2.0.0.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1306197 13f79535-47bb-0310-9956-ffa450edef68

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -1,6 +1,6 @@
 Hadoop Change Log
 
-Release 0.23.3 - UNRELEASED
+Release 2.0.0 - UNRELEASED
 
   INCOMPATIBLE CHANGES
 

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -1,6 +1,6 @@
 Hadoop HDFS Change Log
 
-Release 0.23.3 - UNRELEASED
+Release 2.0.0 - UNRELEASED
 
   INCOMPATIBLE CHANGES
 

hadoop-mapreduce-project/CHANGES.txt

@@ -1,6 +1,6 @@
 Hadoop MapReduce Change Log
 
-Release 0.23.3 - UNRELEASED
+Release 2.0.0 - UNRELEASED
 
   INCOMPATIBLE CHANGES