Add a user_id column to the modx_sessions table

[muzzwood]

Feature request

Summary

Add a user_id column to the modx_sessions table. When a session is created, if we have a user id, set it there.

Why is it needed?

This will allow easy access to all of a user's sessions, if you want to force a single user out of all their sessions you can delete all records for their user id. Currently the modx_user_attributes table has a sessionid column that stores the most recent session id, but it overwrites any previous ones. So the user keeps access to those.

Suggested solution(s)

Adding a user id to the table should work. There may be a reason I'm unaware of making this a bad idea though, so if there is feel free to tell me to go away :D