Fixes Roles to work with rainlab.user and adds key to User relation

[firemankurt]

Please add 'key' => 'user_id' to definition to help other plugins avoid issues when extending the user plugin. See: https://octobercms.com/forum/post/model-extending-base-rainlabuser-model-is-triggering-shahiemseymorroles-in-backend-form-causing-sql-error

[firemankurt]

Fixes Roles to work with rainlab.user

This will use RainLab\User\Models\UserGroup for group storage and
ShahiemSeymor\Roles\Models\UserPermission for permision storage.

Still need to create a migration to move existing groups from ShahiemSeymor\Roles\Models\UserGroup to RainLab\User\Models\UserGroup

[firemankurt]

Use this query to copy groups over:

REPLACE into user_groups (id, name, description, created_at, updated_at)
select id, name, description, created_at, updated_at FROM shahiemseymor_roles

REPLACE INTO users_groups ( user_id , user_group_id )
SELECT user_id , role_id FROM shahiemseymor_assigned_roles