Fixes stub_authorization! for RSpec 3.
Fixes #5182
Reimbursement email
Fixes #5185
Display return acceptance errors in Admin UI

So admins know what rule caused an item to be rejected or placed in the manual_intervention_required state.
Fixes #5186
Add preference for automatically restocking returned items
Fixes #5188
Don't allow adding products to order if it's already shipped.
Fix typo.
Remove new & edit Admin pages for reimbursement types

These are managed through code rather than the Admin UI.
Leave an index page to display the current state.

Also:
  - Fix a migration. It was failing silently because of cached column information