Adding Organizations, tweaking Sponsor

Hi,

This adds an Organization group. Organizations take two fields (Drupal Association and Our Modules) that were previously in Sponsor. They are subsequently removed from the cod_sponsor Feature (but I think Features won't do that automatically; you have to do it manually). Also adds a "group_org_user" field to user entities so that Organization memberships are separate from other memberships.

I didn't affect the display of Sponsors OR Organizations. But I could if need be. I have a little more time this week than last.