Updated CHANGES.txt to reflect hadoop-2.6.0 release dates.

(cherry picked from commit 770cc144425b6188d9b93178c77a35cd830a60df)

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

@@ -74,7 +74,7 @@ Release 2.7.0 - UNRELEASED
     HADOOP-11187 NameNode - KMS communication fails after a long period of
     inactivity. (Arun Suresh via atm)
 
-Release 2.6.0 - UNRELEASED
+Release 2.6.0 - 2014-11-15
 
   INCOMPATIBLE CHANGES
 

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

@@ -155,7 +155,7 @@ Release 2.7.0 - UNRELEASED
     HDFS-7366. BlockInfo should take replication as an short in the constructor.
     (Li Lu via wheat9)
 
-Release 2.6.0 - UNRELEASED
+Release 2.6.0 - 2014-11-15
 
   INCOMPATIBLE CHANGES
 

hadoop-mapreduce-project/CHANGES.txt

@@ -12,7 +12,7 @@ Release 2.7.0 - UNRELEASED
 
   BUG FIXES
 
-Release 2.6.0 - UNRELEASED
+Release 2.6.0 - 2014-11-15
 
   INCOMPATIBLE CHANGES
 

hadoop-yarn-project/CHANGES.txt

@@ -45,7 +45,7 @@ Release 2.7.0 - UNRELEASED
     YARN-2713. "RM Home" link in NM should point to one of the RMs in an 
     HA setup. (kasha)
 
-Release 2.6.0 - UNRELEASED
+Release 2.6.0 - 2014-11-15
 
   INCOMPATIBLE CHANGES