Revert PIG-3457: Provide backward compatibility for PigStatsUtil and JobStats

git-svn-id: https://svn.apache.org/repos/asf/pig/trunk@1530088 13f79535-47bb-0310-9956-ffa450edef68
PIG-3506: FLOOR documentation references CEIL function instead of FLOOR

git-svn-id: https://svn.apache.org/repos/asf/pig/trunk@1530147 13f79535-47bb-0310-9956-ffa450edef68