Postgres has support for timestamps "infinity" and "-infinity"
<http://www.postgresql.org/docs/8.3/interactive/datatype-datetime.html#DATATYPE-DATETIME-SPECIAL-TABLE>, but when
these are retrieved via a query they are converted to `today 00:00:00`. This is an improvement compareed to older version
where something crashed, but still it's not usable.

The attached patch contains a fix for this, but I'm not sure if this is the best way to fix this. Possible other databases
than postgresql have support for infinite timestamps as well, which means the fix should probably move somewhere to
the DBD modules.