HIVE-5278 : Move some string UDFs to GenericUDFs, for better varchar support (Jason Dere via Ashutosh Chauhan)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1523518 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk-gd