mvc framework required to implement sponsor_osra_id

part of PT story https://www.pivotaltracker.com/story/show/75999516

- *** This does not create a sponsor_osra_id yet ***
- model with validation that 1 and only one branch or oganisation is selected
- migration to add organization reference to sponsor
- belongs to organization reference in model
- specs to check 1 branch or orgnaization has been selected
- fixed sponsor factory so it is valid against new criteria
- fixed feature files to  reference a branch so they can be valid
- changed active admin form to show the organization and branch drop downs
added generation of sponsor_osra_id functionality

part of PT story https://www.pivotaltracker.com/story/show/75999516
- added sequential_id field and osra_num field to sponsor table
- implemented tests for osra_num functionality
- implemented osra_num functionality
refactored validation to reduce amount of code

Part of PT story https://www.pivotaltracker.com/story/show/75999516
added spaces in between braces to comply with project coding standards

part of PT story https://www.pivotaltracker.com/story/show/75999516
improved wording on description of affiliation tests based on code review

part of PT story https://www.pivotaltracker.com/story/show/75999516
refactor improved clarity and intent of afilliation tests

part of PT story https://www.pivotaltracker.com/story/show/75999516
refactor of osra_num tests

part of PT story https://www.pivotaltracker.com/story/show/75999516
refactor osra_num test to improve clarity

part of pt story https://www.pivotaltracker.com/story/show/75999516
thanks @NikitaAvvakumov
used build_stubbed instead of build for branches and organizations

part of PT story https://www.pivotaltracker.com/story/show/75999516
Basic Model and Spec for OrphanList
Spec for OrphanList model
Add sequential_id to Orphan List
Added OrphanList to ActiveAdmin. Introduced functionality to upload files for OrphanList.
Added Index and Download action.
Update specs with latest validation changes in OrphanList model
Removing file field from orphan_lists table
Introduced Paperclip and replaced the old file handling functionality with it
All existing tests are passing
Nested lists under partners and added upload action to partner show view
Upload list available only to Active partners