Requested orphan count

request orphan count pivotal tracker story https://www.pivotaltracker.com/story/show/79157380

- create migration
- change active admin views to show fields
- added validation
- refactor tests and factories to conform to new requirement

Jira:
OSRA-83 #resolved
OSRA-84 #resolved
OSRA-85 #resolved
OSRA-86 #resolved
Let's randomize? e.g. `(0..10).to_a.sample`