Restricting certain fields for trogdir people

These fields are disabled on the form, but you could technically still
submit them. This commit limits what fields the user can update at the
controller level.
WCMS-113 added basic slug to department, group, and people controllers, and added person bio slug addition field
WCMS-113 showing slugs on departments, groups and person bio forms
looks better with the sort
Merge branch 'master' into slugs

Conflicts:
	app/views/groups/_form.html.slim
fix version 2 (complete)
Updating buweb_content_models
Slugs didn't get added until v0.26.0
added slug permanency note
WCMS-202 Removed services.
WCMS-202 Renamed "Departments" nav item to "Offices & Services"
WCMS-217 Removed Activities from BioEditions
Merge branch 'master' into slugs
Merge branch 'master' into remove_services
Merge branch 'master' into slugs

Conflicts:
	app/controllers/departments_controller.rb
Merge branch 'master' into remove_services
Fixed activity log not logging 'create' for memberships
WCMS-209 Added code restricting the syncing of department and title exclusively for student workers.
Conversely, if the person is any combination of student worker and employee, faculty or volunteer their department and title will still be synced.
Merge pull request #55 from biola/membership_activity

Fixed activity log not logging 'create' for memberships
changed to set slug
Added suggested_slugs as a helper method.
NOTE: the existing method in buweb_content_models should get removed

Added an add-on with the directory url to give you a context of what you are selecting when setting the slug.