PIG-3970: Merge Tez branch into trunk

git-svn-id: https://svn.apache.org/repos/asf/pig/trunk@1598702 13f79535-47bb-0310-9956-ffa450edef68
PIG-3971: Pig on tez fails to run in Oozie in secure cluster (rohini)

git-svn-id: https://svn.apache.org/repos/asf/pig/trunk@1598709 13f79535-47bb-0310-9956-ffa450edef68
PIG-3976: Typo correction in JobStats breaks Oozie (rohini)

git-svn-id: https://svn.apache.org/repos/asf/pig/trunk@1598779 13f79535-47bb-0310-9956-ffa450edef68