isValid availability

Hello,

The method isValid is implemented and committed since 2012-01-19 by
Dave Cramer, however, it isn't available on the driver version 901 and
902.

Any reason why?

On the same subject, the implementation is using SELECT 1; because it
was the simplest query returning a value, simply issuing an "" won't
guarantee to go to the back-end (it may go for now, but it depends on
the driver bottom layer to issue it to the back-end. And the is no
real performance advantage from "" to "SELECT 1" since no one is going
to call isValid hundreds of times a second.

I also noted that the driver release dates on the site are incorrect
(http://jdbc.postgresql.org/changes.html) for driver 901 and 902
(copy/paste is evil).

Thank you all,

Luis Flores