HIVE-4030 : Name windowing function in consistence with sql standard (Ashutosh Chauhan)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/ptf-windowing@1446936 13f79535-47bb-0310-9956-ffa450edef68
HIVE-4031 : Add apache headers in new files (Ashutosh Chauhan)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/ptf-windowing@1446937 13f79535-47bb-0310-9956-ffa450edef68