Saving UTC Offset in Postgres DATETIME messes with PHP DateTime and Timezones

The DateTime type is currently unusable in PostgreSQL due to a wrong parsing format.

PostgreSqlPlatform::getDateTimeFormatString() should be changed from:

Y-m-d H:i:sO

to

Y-m-d H:i:s.uO

According to http://twitter.com/auroraeosrose/statuses/16154268629

Also, there's no way to check if a convert From and To PHP/Database worked correctly. Maybe we should introduce an exception when a DBAL\Type conversion fails, otherwise, there's no way to figure it out what happened.