drill

4e2df00e - DRILL-3198: Fix: DatabaseMetaData.getTypeInfo(...), etc., return null.

DRILL-3198: Fix: DatabaseMetaData.getTypeInfo(...), etc., return null. Fixed DatabaseMetaData.getTypeInfo(...) and similar methods enough to not return null. (Each method now returns a ResultSet representing a result set with zero rows, though not with JDBC-specified columns.) - Changed utility method getEmptyResult(). - Added basic test methods. - Added interface DrillDatabaseMetaData (for place to document current Drill-specific behavior). - Added Javadoc for current behavior.