DRILL-4332: Makes vector comparison order stable in test framework
In the test framework, a vector is a map of <String, Object>. When comparing
actual values with baseline, the comparison is made column by column, but
a HashMap key ordering is not guaranteed, and the ordering actually changed
between Java7 and Java8 in Oracle/OpenJDK.
Replacing HashMap with TreeMap which has a guaranteed ordering by design.
Small update by jason during merge, fixed test failure on JDK 7 due to map key ordering,
just replaced two more uses of HashMap with TreeMap.
Closes #389
