* Moving the "Null" user object closer to User
Prior to this commit, we had the presentation concept of a DELETED_USER
in the ApplicationHelper. Further, we did type checks against that
object instead of relying attributes of the object.
With this commit, I moved the "Null" user closer to the User definition
to help highlight the concept that there might be deleted users.
I didn't remove all of the type checks, but did attempt to create a more
"duck-type" object.
Further, I moved away from an OpenStruct which in the past (and perhaps
present) had performance issues.
* Moving DeletedUser into Users module space
0a1b222bb7