PHP native session  & Linux compatibility when using ORM Auth

PHP native sessions will choke when storing ORM objects with a high number of relationships.  Adding functions to convert ORM user objects to and from arrays.

ORM auth on Linux throws errors on the class case. Update to fix.
This line will be called every time we do `Auth::instance()->get_user()`, I don't know if ORM does some caching or if it revisits the database every time. You should benchmarked this, and guarantee good performance for everybody.