#259 Minor Ruby Driver Issues

[Jira Trac]

The following issues were reported by an affiliate user. They aren't really bugs, but still should be fixed:

1) There is a printf statement left on line 52 of stmt.c in the ruby driver, causing all queries to be logged to stdout. That should be removed, or at least only turned on if a debugging option is enabled.

2) Bigint types should be returned as ruby Integers/Bignums, not as ruby Strings. Date types should be returned as ruby Date instances, not as ruby Time instances. Numeric types should be returned as ruby BigDecimal instances, not as ruby Floats (using Floats loses precision). ruby Date and BigDecimal are not core ruby, but are in ruby stdlib (require 'date' and require 'bigdecimal').

3) In ruby, libraries should not raise instances of StandardError.
Libraries should create a subclass of StandardError and raise instances of that subclass. There should be a Cubrid::Error subclass of StandardError, and all exceptions raised by Cubrid should raise instances of Cubrid::Error.

4) There's no Cubrid::BIGINT constant for the bigint type number (21).