Rudimentary analytic planner:
a minimal set of changes in order to generate single-node plans for queries containing a single AnalyticExpr

Change-Id: I5b70a00262f300e4a345907d9cfbc627502ce348
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/3880
Reviewed-by: Alex Behm <alex.behm@cloudera.com>
Tested-by: jenkins
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/3901
Reviewed-by: Marcel Kornacker <marcel@cloudera.com>