Renamed a column named "timestamp" in the security package because this is now a reserved word in PG (correctly). I changed the Oracle version, too, because I know that 9i has added the "timestamp" datatype and even if it will accept it as a column name it's confusing.
I also changes postgresql.sql to load correctly under PG 7.1 and 7.2.
bootstrapper can now load either the Oracle or PostgreSQL acs-kernel datamodel. It checks on-the-fly for which db is configured in the OpenNSD database pools allocated to OpenACS. Only acs-kernel is correctly self- configured at this point.