Fixes for older server versions

Francisco,

Here are fixes for the array problem you found on 8.4, plus some changes to tests to make them run properly on more various versions.

I tested Npgsql on every final version of 8.0, 8.1, 8.2, 8.3, 8.4, 9.0, 9.1, 9.2, and 9.3 :)

-Glen