Connection Properties for FetchSize and Autocommit

Hi pgjdbc coders,

I recently had to deal with a 3rd party application (without source code)
that processed large result sets, and kept running out of memory on the
client. I realise this was because the application didn't set a fetch size,
nor turn off autocommit and so the criteria for the driver to use a
cursor-based result set were not met.

Since I cannot modify the application, I instead altered the postgresql jdbc
driver instead to allow two additional driver parameters - defaultFetchSize
and defaultAutoCommit to override the built-in defaults (0 and true).

Anyway, it worked well for me, so for what its worth a diff is attached.
All test cases still pass. If you think this is worth pursuing, let me know
what else needs to be done!

David Langton