Move User data from $user->data array to fields attached to user

This would allow for much easier integration with other modules such as feeds, but requires a fair amount of work to implement including an update script that moves existing users' data. Fields would be hidden fields manipulated only through code.

e.g.

- ldap_authentication_puid_field
- ldap_authentication_puid_value
- ldap_authentication_sid
- ldap_authentication_dn
- ldap_authentication_mail
- ldap_authentified = boolean

- ldap_authorization_ = repeating field of authorization ids