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.
Merge branch 'master' into limit_people_controller_edit_fields

Conflicts:
	app/controllers/people_controller.rb
Merge pull request #56 from biola/limit_people_controller_edit_fields

Limit people controller edit fields