HADOOP-10820. Throw an exception in GenericOptionsParser when passed an empty Path. Contributed by Alex Holmes and Zhihai Xu.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1617543 13f79535-47bb-0310-9956-ffa450edef68
Merge r1617555 from trunk. YARN-2373. Changed WebAppUtils to use Configuration#getPassword for accessing SSL passwords. Contributed by Larry McCay

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1617557 13f79535-47bb-0310-9956-ffa450edef68