Release process for 2.7.2: Set the release date for 2.7.2

(cherry picked from commit ec4d2d9f40c1cb52ca4561b3d010ffc046a73495)

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

@@ -45,7 +45,7 @@ Release 2.7.3 - UNRELEASED
     HADOOP-12706. TestLocalFsFCStatistics#testStatisticsThreadLocalDataCleanUp
     times out occasionally (Sangjin Lee and Colin Patrick McCabe via jlowe)
 
-Release 2.7.2 - UNRELEASED
+Release 2.7.2 - 2016-01-25
 
   INCOMPATIBLE CHANGES
 

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

@@ -68,7 +68,7 @@ Release 2.7.3 - UNRELEASED
     HDFS-9625. set replication for empty file failed when set storage policy
     (DENG FEI via vinayakumarb)
 
-Release 2.7.2 - UNRELEASED
+Release 2.7.2 - 2016-01-25
 
   INCOMPATIBLE CHANGES
 

hadoop-mapreduce-project/CHANGES.txt

@@ -31,7 +31,7 @@ Release 2.7.3 - UNRELEASED
     MAPREDUCE-6554. MRAppMaster servicestart failing with NPE in
     MRAppMaster#parsePreviousJobHistory (Bibin A Chundatt via jlowe)
 
-Release 2.7.2 - UNRELEASED
+Release 2.7.2 - 2016-01-25
 
   INCOMPATIBLE CHANGES
 

hadoop-yarn-project/CHANGES.txt

@@ -78,7 +78,7 @@ Release 2.7.3 - UNRELEASED
     YARN-4598. Invalid event: RESOURCE_FAILED at
     CONTAINER_CLEANEDUP_AFTER_KILL (tangshangwen via jlowe)
 
-Release 2.7.2 - UNRELEASED
+Release 2.7.2 - 2016-01-25
 
   INCOMPATIBLE CHANGES