Org crud

changes to @betasve pr to comply with latest requirments of client

based on PT story https://www.pivotaltracker.com/story/show/77974308
- Removed Region from
  - migration
  - active admin
  - rspec tests
  - cucumber tests

- Remove sequential_id migration completely

- Removed link to organisation on active admin menu
  - urls still work when typed in manually
  - delete is disabled in active admin
  - changed cucumber test to verify absence of organisation link in menu

No its not going to far and normally its what I would do, but I am going to disappoint you :monkey_face: Because the migration hasn't touched anything at all yet I removed the migration that added the sequential_id completely and modified the original migration to remove the branch column.