HADOOP-8415. Add getDouble() and setDouble() in org.apache.hadoop.conf.Configuration (Jan van der Lugt via harsh)
Merging into branch-2. Updating CHANGES.txt


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1461727 13f79535-47bb-0310-9956-ffa450edef68