The language were set only on session. But now it is
stored with user profile, on DB.
It is important as now I can send alert e-mails to each
user on their own languages and not the activer
user language.
Also, wherever the user logs out and logs in again,
it will see the same site locale.
I had included item_id and user_id as primary keys to avoid duplications
but the command line to attach I am using does not duplicate.
Not only that, I got an error during migration of Multiple primary keys.
