drill

3b056db0 - DRILL-4459: Resolve SchemaChangeException while querying hive json table

DRILL-4459: Resolve SchemaChangeException while querying hive json table - Replace drill var16char to varchar datatype for hive string datatype - Change testGenericUDF() and testUDF() to use VarChar instead of Var16Char - Add unit test for hive GET_JSON_OBJECT UDF closes #431