If you would like to use the new driver, you should add the user_id (nullable integer), ip_address (nullable string), and user_agent (text) columns to your session database table.
To my knowledge the database is created by the migrations so there should be a hint to this, but looking into the Laravel git repository I can't spot any difference: https://github.com/laravel/laravel/blob/master/database/migrations/2014_1012000000_create_users_table.php (it seems that the markup doesn't like this link... I miss the good old [URL] syntax :S)
How am I supposed to do that? What should I actually do?
If you would like to use the new driver, you should add the user_id (nullable integer), ip_address (nullable string), and user_agent (text) columns to your session database table.
If you're migrating from 5.1 up to 5.2, here's a migration that just adds the new fields. It's not that it's hard to write, but it is odd that there's not one pre-tested in the docs.