setting advanced_agg mode to True.
This makes this test suit consistent with the online version of YSMart.
OPEN - task 1: YSmart generates different output for tpch queries 3, 17,
18, 21 
http://github.com/meisam/YSmart/issues/issue/1

The problem was that correlation.ysmart_correlation(tree_node) was not
being called on the query plan tree before generating MapReduce jobs.