[PATCH] PostgreSQL timestamp with zone type support

The current Rails practice with PostgreSQL is to use timestamp without zone and use ActiveRecord's time zone handling. This works fine for Rails but makes it slightly inconvenient for ad hoc, local time queries outside of Rails. With this patch ActiveRecord sets the connection time to UTC when creating the connection if AR::Base.default_timezone is :utc. Rails can then handle time zones its way and other clients can use PostgreSQL's time zone handling.