GROOVY-3048 callWithRows() for StoredProc using Output Params and a ResultSet

Added new callWithRows() methods for handling Stored Procedures that use both Output Parameters and a single ResultSet.

The main callWithRows method is essentially identical to the original call() method, but with an extra few lines to return the ResultSet rows. I also took care to make sure the original call() method was not affected by the additions.

Also added test cases for Stored Procedures for the existing call() and rows() methods as well as the new callWithRows() methods. The gradle test cases work against hsqldb. I've also tested the code against a db2 stored procedure.

These changes were originally discussed in this blog post:
http://www.objectpartners.com/2014/01/24/simpler-stored-procedures-with-groovy/

I welcome any and all comments, thanks!