Eng 6390 jdbc resultset

Wrote the test cases (as per issue description) for HSQL JDBCResultSet and VoltDB JDBC4ResultSet (for Empty and Non-Empty tables) and compared the corresponding results.

Fixed the cursor navigations in the scrollable JDBC4ResultSet for forward and backward navigations and all the boundary cases.
After this point, I would check for row is negative and turn it into a row number relative to the beginning of the table. That way you can check the boundaries consistently.