Unused Sponsors

> My guess is for larger COs we don't want to populate $sponsors if sponsors
> aren't in use, since it could be a big chunk of data.

$sponsors is set in both co_person_roles_controller and co_people_controller.

It's used by the views to render both of these pages:
gears/co_people/edit/1/co:1 (to display name of Sponsor)
gears/co_person_roles/edit/4/co:1 (to feed into dropdown for Sponsor selection)

We'll need to
1) views: keep the sponsor fields from showing up if sponsors are not being used
2) controller: not populate $sponsors