PIG-3745: Document auto local mode for pig (aniket486)

git-svn-id: https://svn.apache.org/repos/asf/pig/trunk@1594619 13f79535-47bb-0310-9956-ffa450edef68
PIG-3545: Seperate validation rules from optimizer

git-svn-id: https://svn.apache.org/repos/asf/pig/trunk@1595278 13f79535-47bb-0310-9956-ffa450edef68
Merge latest trunk changes


git-svn-id: https://svn.apache.org/repos/asf/pig/branches/tez@1595392 13f79535-47bb-0310-9956-ffa450edef68