Provide CRUD operations for an Organization

[whytheplatypus]

As a staff user of smh_app I need to be able to model my organization and associated staff.

• [x] Organization model
• [x] CRUD for Organization model by a logged in user
• [x] Management of users associated with an organization

Initial Organization model (proposed):

{
    slug     string <unique>
    name   string <unique>
    users   many to many
}

[whytheplatypus]

closed by #15