Fix bug of join filter doesn't work in JoinOperator

JoinFilters were ignored in JoinOperator, queries like:

"SELECT src1.key as k1, src1.value as v1, src2.key as k2, src2.value as v2 FROM src src1 RIGHT OUTER JOIN src src2 ON (src1.key = src2.key and src2.key < 20 and src1.key < 20);"

The filter conditions didn't take effect. This patch will solve the bug. 

BTW: I notice that the Hive-0.9 seems give the wrong result for above query.