HADOOP-9231. Parametrize staging URL for the uniformity of distributionManagement. Contributed by Konstantin Boudnik.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1437140 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9231. Add missing CHANGES.txt

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1437143 13f79535-47bb-0310-9956-ffa450edef68