Review permissions

* Added users controller and index view
* Added pretender for impersonation
* Updated each of the edit pages to only show sub-pages that the user is allowed to see.
* The permissions are now controlled in each pundit policy
Hmm... I guess that is a little confusing. The membership page on the person profile is read only, so they are only allowed to see what departments and groups they are in. To edit memberships you have to have permission on the department or group.