ADOOP-9643. org.apache.hadoop.security.SecurityUtil calls toUpperCase(Locale.getDefault()) as well as toLowerCase(Locale.getDefault()) on hadoop.security.authentication value. (markrmiller@gmail.com via tucu)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1504966 13f79535-47bb-0310-9956-ffa450edef68
merge -c 1504970 from trunk to branch-2 to fix YARN-919. Document setting default heap sizes in yarn env.sh Contributed by Mayank Bansal.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1504971 13f79535-47bb-0310-9956-ffa450edef68